AFL Statistics Series #1: Which Statistics Matter The Most (Apart From The Scoreboard)?

Introduction

This is a first in a series of posts that I’ll do about statistics in the Australian Football League. The posts will be about which AFL statistics I think matter – that is, what I think they tell us about how AFL teams and players go about scoring and stopping the other team from scoring.

Yes, there is a lot of writing out there already about AFL that uses statistics and numbers, and a lot of good writing. This is just how all of those statistics make sense to me. I hope if you’re reading this you find something in here that’s useful for you too.

A lot of the thoughts I’m going to talk about here came about as a result of me trying to devise a method of rating AFL players, without having access to the detailed data that Champion Data use to devise their ratings. We may still get to that in the end. It turns out though that to work out how each player contributes to winning a game you need to first think about how teams go about winning them.

Points differential: the most important statistic of all (duh…)

In their AFL Prospectus 2018, Champion Data made this obvious but important point:

“… we are asked [:] What’s the most important stat? As respectfully as possible we answer with POINTS FOR. It’s the one stat that guarantees a win … We go on to explain it’s more about how you get to that point.”

Of course points for compared with points against is important. There is a position here though that may not be quite so obvious. Some would argue that only the win or the loss matter, and not the margin of victory or defeat. Margins though tend to be a better predictor of future performance. Close wins may bring exhilaration and relief, but in general a team should take more comfort out of a comfortable win than a close one.

Metres gained matters

Metres gained gets some bad press, perhaps because it sounds like ‘a stat too far’. An article on The Roar last year even went so far as to call the statistic ‘irrelevant’. The main argument was that it doesn’t take into account the outcome of the possession – a long kick to the opposition would be credited with many more metres than an effective handball backwards to a teammate. “While it is impressive to see a player average over 300 metres gained a match,” the author says “the statistic is mostly empty in its meaning.”

The article makes some good points, but I disagree that metres gained is irrelevant. Indeed to me, there is hardly anything more fundamental to performing well at Australian rules football than gaining metres. When you’re watching your team, apart from when they’re actually in the action of kicking goals, what do you most want them to do? You want them to GET THE BALL CLOSER TO THEIR GOALPOSTS and GET THE BALL FAR AWAY FROM THE OTHER TEAM’S GOALPOSTS!

Now a critic of metres gained may point out that it isn’t so great if you kick 50 metres straight to the opposition. That’s true – ‘effective’ metres would probably be a better measure. We’ll get to more about keeping possession later.

Kicking the ball 50 metres to the opposition though isn’t necessarily a horrible outcome, despite what I will say later on about the value of turnovers. Now if the opposition run the ball down the field and score a goal off your turnover that is obviously a bad result. That worst-case scenario is relatively uncommon though – only about 10 per cent of possession ‘chains’ end in goals, and on average those ‘chains’ only last for about three disposals and gain about 45-50 metres. In other words, even if you kick 50 metres to the opposition it’s unlikely the other team will punish you by running the ball down the field and kicking a goal (obviously depending on where the ball is, and how badly you butcher the kick). More likely is that the ball may come back to your team within a few possessions, and back around where you started.

What about an effective kick across the ground that gains no metres but sets the team up for a shot at goal? Isn’t it true that metres gained isn’t very good at accounting for that? That cross-ground kick however is only valuable if the TEAM gains metres on a subsequent possession. If the opposition stops the ball before it goes any further then it’s just a kick across the ground that didn’t help much. The objection to metres gained here is more about crediting the total metres gained by the team to the individuals in that team – how much did that cross-ground kick help the team to score? – not about the value of the total metres gained by the team itself.

Metres gained matter. In each of the four AFL seasons since the statistic was made public in 2015 no other relatively common used statistic – except statistics directly related to scoring, e.g. score involvements and goal assists – has been more positively correlated with points differential (see table below).

Good teams like West Coast and Richmond had less disposals last year than their opponents, and lower teams like the Bulldogs and St. Kilda had more. Richmond were smashed in hit outs and clearances, and West Coast were behind on tackles. The higher teams though almost always had positive metres gained differentials over the season (see table below). It is one of the few relatively common statistics that you can reliably count on good teams being ahead in.  

[EDIT: Metres gained differential in a single match should, by definition, ALMOST reflect goal differential. Nevertheless, metres gained are still highly correlated with scoring.]    

Once you view gaining territory as an important indicator of a football team’s ability to score goals, the importance of some other AFL statistics falls into place. Inside 50 entries – a statistic that has been noted by others to be highly correlated with winning – indicates metres gained by measuring the number of times a team gets the ball past a particular point on the ground, one it has to pass over in order to score goals. An inside 40 or inside 30 measure would also indicate this.

(Rebound 50s indicate metres gained as well, but since they indicate metres gained in a team’s defensive part of the ground they are negatively correlated with winning. Put inside 50s and rebound 50s together and you get some of the way to a decent proxy for metres gained.) 

It also indicates why the number of kicks that a team or player records is generally important for winning (other than, of course, it is the only way to score goals), and why one kick is generally more important than one handball – more kicks often leads to more territory gained. Conversely though it also explains why just amassing kicks sometimes does not lead to success; for example, two short kicks of 20 metres get a team no closer to goal than one long kick of 40 metres.

All of this is not to say however that an individual player’s contribution to their team’s performance should be primarily measured by metres gained. The AFL leaders in metres gained per game last year were Jayden Short, James Sicily, and Nathan Wilson. Nobody thinks that these are the very best players in the league. (Maybe they should … but probably not.) That is because what these players don’t do as much as some other players is win their teams the ball in the first place.

Turnovers are the main source of scoring shots

In Australian rules football, the significance of individual possessions in helping a team score can sometimes seem hard to work out. The ball can pass back and forth between teams several times before anyone has a legitimate chance to score. Teams can also have very different styles when in possession of the ball, with some teams preferring a ‘high-possession, low-risk’ game, and others preferring to be more direct.

Let’s try and simplify it then. Obviously if you have possession of the ball you are the only team that can score until your ‘chain’ of possessions is broken. We’ll call any unbroken sequence of possessions by a team – whether of one possession or ten – a ‘possession chain’.

Let’s say that a possession chain for a team can start in one of three ways:

• the team gets a ‘clearance’ – i.e. it clears the ball from a ball-up, either from a stoppage or a centre bounce at the start of a quarter or after a goal
• the opposition turns the ball over; or
• the opposition scores a behind, giving the team a kick into play.

Let’s also say that a possession chain ends in one of three ways:

• the team scores a goal or behind – a successful (or at least partially successful) possession chain;
• the team turns the ball over; or
• the possession chain is ‘stopped’, due to a ball-up, or because the quarter is over, or because the scoreboard is on fire – basically any unsuccessful possession chain that does not result in the ball going directly back to the opposition.
  

(That may not be completely technically correct according to how Champion Data defines these terms, but I think it’s close enough for the purpose of my main point here.)

Therefore, for a team we will say that:

Possession chains started = Possession chains ended

Clearances + Opposition turnovers + Opposition behinds = Scoring Shots + Turnovers + Stopped Possession Chains

Or, more importantly:

Scoring Shots = Clearances + Opposition turnovers + Opposition behinds - Turnovers - Stopped Possession Chains

For example in 2018 premiers West Coast averaged 24.7 scoring shots per game. By the definition above they started 117.9 possession chains per game, from 36.6 clearances, 71.6 opposition turnovers, and 9.7 opposition behinds. Of the 93.2 unsuccessful possession chains they had per game, 67.7 of them were turnovers, and 25.4 were stopped possession chains.

The bottom team in 2018 Carlton averaged 17.9 scoring shots per game. By the definition above they started 109.7 possession chains per game, from 35.0 clearances, 62.3 opposition turnovers, and 12.4 opposition behinds. Of the 91.9 unsuccessful possession chains they had per game, 67.3 of them were turnovers, and 24.6 were stopped possession chains.

What’s the main difference in the possession chains of those two teams? Clearances, behinds, and stopped possession chains are all similar. The main difference is West Coast started more chains through opposition turnovers – about the same difference as the difference in scoring shots.

Returning to our scoring shot formula above, let’s now look at scoring shot differentials, or scoring shots for the team less opposition scoring shots. With a bit of mathematics we can show that:

Scoring shot differential = Clearance differential – 2 * Turnover differential – Behinds differential – Stopped possession chains differential

Maybe it’s just me, but I found this really interesting when I worked it out. Turnovers are not only more common than those other components they count for twice as much in this equation. When there is a stoppage one team’s possession chain ends, but then each team has about a 50 per cent chance of starting the next possession chain. When the ball is turned over, one team’s possession chain ends and the other team’s begins.

The importance of turnover differential can be seen when we compare how teams got their scoring shots in 2018 (see table below). Minor premiers Richmond were last by some margin in clearance differential, but they were way ahead in terms of (inverse) turnover differential. West Coast and Melbourne also rated highly in either causing opposition turnovers, or not turning the ball over themselves. Unsurprisingly, bottom teams Carlton and Gold Coast rated poorly in terms of turnover differential.

Turnover differential does not explain everything, as there are other ways to start possession chains. 2018 runners-up Collingwood gave up a lot of turnovers, but they were good at getting clearances. 2016 premiers the Western Bulldogs were fantastic at winning clearances. It is just that it is less likely to get a high differential through clearances or stoppages rather than turnovers as there are less of them. Hence, clearance differential is less correlated with winning than turnover differential is.

In terms of valuing players this suggests that not only are players with high clearance numbers such as Tom Mitchell and Nat Fyfe important for starting possession chains, but so are defenders who get a high number of intercepts such as Alex Rance and Jeremy McGovern. Though the question then is how important is the individual player who records the clearance or intercept to the team getting possession? How much of the credit should go to the ruckman getting the hit out, or the structure of the team defence?

Given how fundamental I said metres gained were how then does turnover differential relate back to that measure? If the main aim of Australian rules is to score by getting the ball close enough to your goal to do so, then the way to progress the ball down the ground is to get possession of the ball and keepisng it. The best possessions are those that help the team to gain a high number of metres with a relatively low risk of giving the ball back to the opposition, or of the ball being ‘stopped’. On defence, your aim is to stop the other team doing this.

Sounds simple, right? Well, it’s easier said than done. Also, what may be complex about Australian rules is the many ways you can go about doing this.

Goal accuracy: converting those shots at goal

Another statistic that I think is important is goal accuracy, though not quite in the same way as the other main statistics I have covered above.

Goal accuracy – the percentage of shots a team has on goal that are goals (scoring shots, if kicks out of bounds are not available) – is somewhat important to performance over an entire season. Last season, finals teams Sydney, Hawthorn, Collingwood and West Coast were good at it, but Richmond and GWS were not. In 2017 the leaders in goal accuracy were non-finalists Melbourne and the Brisbane Lions. Scoring shot creation is generally more important to performance over a season than scoring shot conversion is, with teams being reasonably close over a season in terms of the rates at which they convert.

I would say where it matters more is changing the outcome of a single game, which is even more important if that game is a final. In a single game there is more variability in scoring shot conversion than over a season, and the results can swing the match significantly. We see this in some of the comparisons between final scores and ‘expected scores’ for a game.

To state the obvious, six behinds are needed to gain as many points as a single goal. Given that the difference between premiers West Coast and last-placed Carlton was only about seven scoring shots per game you want to convert those chances when you get them. Or given that goal accuracy tends to even out over the season, you want to convert those chances when they are most important. (West Coast almost didn’t in last year’s Grand Final, until Dom Sheed did.)

Conclusion

In Australian rules football the ways for teams to score are:

•  get possession of the ball, and keep it;
• gain metres while you have the ball in order to get a shot at scoring; and
• get as many of those shots at scoring through the goal posts as possible.

For defence the ways to stop the other team from scoring are:

• try to get back possession of the ball, or otherwise get a stoppage;
• if you haven’t got the ball back yet stop the other team from getting the ball down the field far enough to have a shot at scoring; and
•  if the other team does get a shot a scoring, try and limit the chance that it is a goal.

This is essentially how I am going to talk about the value of AFL statistics in this series. I’ll mainly evaluate teams and players by how good they are at doing these things. I also plan to talk about how the evolving nature of statistics has given us a better picture over time of the effectiveness of teams and players. Some conclusions will be obvious, but some may be less so. In the end, we may yet even get to that 'player rating' system.

AFL Power Rankings: Finals 2018

It was an even AFL season at the top, but when the West Coast Eagles had their two big forwards they were perhaps a touch above the rest.

In terms of top AFL teams, 2018 was a weird season. No team appeared to be as strong as the ‘great’, or even very good sides of recent years, with Richmond the only team during the season to get close to that level. Arguably the best teams going into the finals series – Richmond, Melbourne, and Geelong – all had big losses that eliminated them from the finals, while ‘mid-range’ good sides Collingwood and West Coast emerged as the in-form teams in September.

The result is it’s pretty hard to say, standing at the end of the 2018 season, who the strongest team of the year actually was. We do now know who the premiers were though.

Maybe the ‘top’ team was the Eagles all along

My ranking system, like many other AFL ranking systems, does not account for players missing through injury. Generally this probably doesn’t matter too much, unless a team has an ‘epidemic’ of them. There is enough evidence through the season however to say that this year’s premiers, the West Coast Eagles, were a much better side when their two big forwards – Josh Kennedy and Jack Darling – were available.

First, the main statistic: the Eagles were undefeated at 13-0 when both Kennedy and Darling played, and 6-6 when one of them was missing. Wins and losses can sometimes be a bit deceiving, because it depends on who you played, but that is enough games to suggest that something was different.

We can also look at the Eagles’ adjusted net margin – i.e. their net margin adjusted for estimated home ground and opposition strength – to see how much better they were with a full forward line (see chart below). When West Coast were missing either of or both of Kennedy and Darling their adjusted net margin in 2018 was a relatively mediocre +5. When both were in the side it was +28. That’s not historically dominant by any means, but it would have marked the Eagles out as the top side of 2018.

But perhaps that understates the Eagles a little as well. They had a few struggles to put away bad sides even when they had their two big forwards, beating Carlton by only 10 points, St. Kilda by only 13 points at home, and Fremantle by only 8 points. (These are the negative bars you can see for the Kennedy/Darling games in the chart above.) Against three of the top sides though they had some amazing games, beating Richmond by eight goals, Melbourne by 11 goals in the Preliminary Final, and Collingwood by six goals in their first meeting at the MCG. So with a ‘full’ forward structure they could be really good when it counted most.

West Coast converted more efficiently up forward… except in the Grand Final

Further proof that Kennedy and Darling improved the Eagles’ performance is that the Eagles were considerably better in the area of the ground that those two players could influence the most – namely, up forward.

As pointed out in an ABC article this week by the HPN guys West Coast was averaging almost 2 points per inside 50 with Kennedy and Darling in the side, whereas without those two they were at around the league average of 1.54 points. In other words, with 50 forward entries they would be expected to kick about 100 points with their two big forwards in the side, compared to about 80 points without them. In those aforementioned matches against Melbourne, Richmond, and Collingwood they didn’t have a major advantage getting the ball inside 50 in any of them. The Eagles’ ‘forward efficiency’ loomed as the main way that they could win the Grand Final.

Except that it wasn’t … the Eagles could only kick 79 points from 63 forward entries on the weekend. Collingwood’s defence through the finals was fantastic – holding both Richmond and GWS to under 60 points – and it was almost enough to beat the Eagles as well.

Instead the Eagles won through weight of inside 50 entries, which were 63 to 48 in their favour. Norm Smith Medallist Luke Shuey and Dom Sheed dominated, amassing 70 possessions of which 33 were contested, 17 clearances, and 14 inside 50 entries (Sheed kicked the winning goal to boot). The Eagles’ midfield was fairly decent all season but Shuey shone on Grand Final day. Still with one less goal I would be talking about how good Taylor Adams and Tom Langdon were yesterday instead ... 

That’s it for the 2018 AFL season, and the 2018 rankings. I wouldn’t call it one of the most memorable seasons, but we did have some good matches – the Showdowns, Melbourne v Geelong in the home and away season, Saturday afternoon in Round 20, and fortunately the Grand Final itself. We also don’t really have a strong premiership favourite for next year, which should help to make things exciting. I’m going to rest now, and hopefully come back with some new ideas for 2019.

AFL Power Rankings: Round 23 2018

So at the end of the 2018 AFL home-and-away season Richmond is the top-ranked side, although only narrowly over Geelong and Melbourne.

The Cats and Demons closed the gap considerably over the final two weeks – Geelong from annihilating ‘bad’ teams, and Melbourne from finally beating good teams. The Tigers also slipped a bit, although whether that indicates teams are actually playing better against them or that Richmond was just relaxing a touch before the finals (or both) remains to be seen.

Outside of that, the only highly-ranked team that did not qualify for the finals is Essendon. The Bombers’ high ranking reflects their strong finish to the season, but ultimately their poor start cost them a finals spot.

Predicting the finals series

For the past three years I’ve used the end of home-and-away season rankings to predict how the finals series will play out. Basically this is done just by comparing who has the higher ranking points, adjusted for any estimated home ground advantage.

In that time the Rankings have predicted five of the six Grand Finalists, and two of the three premiers. The miss – like every other AFL ranking system in existence – was the Western Bulldogs in 2016. These predictions however are purely for fun and interest’s sake, and not to coax you into betting your life savings.

Unsurprisingly, the Rankings pick Richmond to win the premiership for a second straight year. Unlike last year though I’d say the Tigers would still be considered the team with the best chance if one considered the likelihood of each team winning each potential match-up, not just the match-ups shown above. I’m picking West Coast, with two home finals from finishing second on the ladder, to be the other Grand Finalist.

Again though, I’ll emphasise three main potential problems with this straight head-to-head prediction method. The first is that just one result going against the prediction can change the outlook considerably. The second point, related to the first, is that our assessment of each team will change as we progress through the finals series.

And the third is that it doesn’t show how close the teams are in likelihood to winning. According to the Rankings there is basically nothing between Melbourne and Geelong. Melbourne should be seen as almost as likely as Geelong to progress as the Cats do above.

I’ll be back again after the finals series finishes with the final rankings for 2018. How soon after, like last year, may depend upon how far my Tigers go.

AFL Power Rankings: Round 22 2018

You have to beat the good sides to win the premiership. Based on their form so far against the likely finalists, which teams should be a bit worried?

Melbourne’s bizarre season 

Today Melbourne qualified for its first AFL finals series since 2006 with an excellent win against the West Coast Eagles. That win aside though, Melbourne’s struggles against the top sides in 2018 have been well noted. They’ve had twelve wins and one loss against teams that are currently in the bottom half on the ladder. Against teams in the top half they’ve had seven losses and just the one win.

Prior to the Eagles match the gap in the Demons’ relative performances against top and bottom half teams was one of the largest in VFL/AFL history. (See this helpful graph from Insight Lane – by a nice coincidence I had already chosen the topic for this week’s post when this insight was given.) Usually good performances against good sides and not-so-good sides tend to go together. Strangely, two of the largest gaps ever in relative performance have come in the past two seasons – last year it was Port Adelaide who confounded rating systems by destroying ‘bad’ teams and capitulating against the good ones.

Melbourne has been highly rated by my ranking system for most of the season, because of its ability to annihilate lower teams. This has left me feeling more and more sheepish as the Demons have racked up losses against the top sides.

The best way to explain Melbourne’s high ranking is this: the Rankings take into account performances against the whole league, not just the top half. It is true that the Rankings have tended to overestimate Melbourne’s chances against the top teams this season. By the same token though, they have tended to underestimate the Demons’ victory margins against the lower teams.

It’s beating the top teams that matters now – which likely finalists should be worried?

However as we get to the finals series, it’s only a team’s performances against the teams that remain that matter. Based on this, once they get past the joy of qualifying for their first finals series in twelve years the Demons should be a bit concerned about their ability to progress.

Melbourne’s average adjusted net margin this season against the other likely finalists is -8 points. After adjusting for opposition strength and home ground advantage this makes them the equivalent of a below average side when they come up against the best (see table below). Richmond, Hawthorn, and Collingwood all won by large margins against the Demons, and Sydney beat Melbourne last week on its home ground.

For the other likely finalists, Collingwood’s inability to beat the top eight teams has also been well noted. The Magpies have only beaten one top eight team: Melbourne (although they came close to beating Sydney). Their best performances have come against the next tier of sides that are just outside the eight – Port Adelaide, North Melbourne, Essendon, and Adelaide. Against the likely finalists they have been the equivalent of an average side. Collingwood and Melbourne are two of the better sides overall, but their ladder positions have been helped a little by friendly fixtures.

Less well noted is GWS’ struggles against the better sides earlier this season. The Giants were thrashed by Geelong, and were also well beaten by West Coast. They have also lost to Sydney twice. Some of those performances may have in part been affected by injuries, but that may not be much comfort to the Giants as injuries have recently hit them again.

Who has done well against the best?

Minor premiers-elect Richmond has performed the best overall against the top teams. The Tigers have had some struggles outside of Victoria, but they have beaten every team they have played in their home state. Unless they lose in the first week of the finals they will play at the MCG for the duration of the finals series.

Also doing well against the top teams are Sydney, West Coast, Hawthorn, and Geelong, although for somewhat different reasons.

Sydney beat the Eagles both at home and away and has also beaten GWS twice this season. Most notably the Swans have had excellent form away from home, beating Geelong, Hawthorn, and Melbourne.

West Coast’s best win for the season was their big win against Richmond at home. They have also shown they are capable of winning in Victoria against good opposition by beating Hawthorn and Collingwood there.

Hawthorn thrashed Melbourne, and also easily beat Collingwood in the first match of the season. The Hawks beat Geelong twice (albeit narrowly), and have generally been close in their losses against the top sides.

Geelong is the second-highest team on the Rankings but will likely finish in seventh or eighth spot on the ladder, in part because of their tough fixture. The Cats’ form against the top teams has been fine: they thrashed GWS, and have been good or at least OK in most of their matches.

You may step it up though

So should we just be waiting for the seasons of Melbourne and Collingwood to come to an abrupt end? Of course not. Last year for example we saw Richmond play considerably better against teams in the finals series than they had done earlier in the season, including a massive (home ground advantage aside) 124 point turnaround against Adelaide. The Western Bulldogs substantially stepped up their performances in September the year before.

Melbourne and Collingwood are good teams. They may even be capable of matching it with the best teams. They just haven’t given a whole lot of evidence during the season that they can yet.

AFL Power Rankings: Round 21 2018

With just two more goals in the past two weeks Port Adelaide would currently be sitting in third position on the ladder. Being near the middle though may be a better reflection of where the Power are at.

History repeats for the Power, but this time they were less ‘unlucky’

The first two chapters of ‘Footballistics’, the AFL analysis book released a few months ago, recount how Port Adelaide lost a home elimination final last year, with an after-the-siren goal by West Coast.

Port Adelaide had been a better side than the Eagles throughout the year, and the book essentially argues they were probably a better side on the night as well. However they lost the match because they were unusually inaccurate in front of goal, and West Coast was the opposite. As a result West Coast finished in the ‘top six’ teams, and Port – though they had been close to finishing in the top four – finished in the ‘middle’ of the ladder in seventh.

This weekend history repeated as the Eagles again beat the Power after the siren at Adelaide Oval. This year though the result more likely reflected that West Coast may actually be the better team.  

The Eagles have improved somewhat in 2018, and currently sit second on the ladder, three wins ahead of Port. Also unlike last year, West Coast easily won the inside 50 count. That indicates this time around the Eagles won because they created more opportunities to score, not because they were uncannily accurate in front of goal.

Port Adelaide have generally been average in 2018

Defenders of Port Adelaide may point out that, with a three-point loss last week to Adelaide, and a four-point loss this week, the Power were only a couple of kicks away from now sitting third on the ladder. On the other hand Port has also won some close matches this year as well, including the first ‘Showdown’ against Adelaide. The Power have three wins and four losses this year in matches decided by 10 points or less, which is neither significantly ‘lucky’ or ‘unlucky’.

Below Richmond there has been a bunch of teams this year that have been pretty good. This includes West Coast, as well as three of the sides in the thick of the battle for third and fourth – GWS, Collingwood, and Hawthorn.

I’d also say it includes Geelong, despite the Cats currently sitting in ninth position – they’ve had a tough fixture, with having to play Richmond, Melbourne, Hawthorn, and Sydney twice. Melbourne and Sydney are a bit harder to pin down after the Swans’ win against the Demons on the weekend: Melbourne’s thrashed the weaker teams, while the Swans have generally struggled in recent weeks.

The Rankings don’t include Port Adelaide in that group. I’m not alone – the mathematically-minded consensus is that Port is ‘splashing about at sea level’. Returning back to a table I showed a few weeks ago the Power have had less ‘good’ and ‘very good’ performances than most of the other teams in the top eight (see table above).

The Power’s two best wins in 2018 have been against Sydney and Richmond. That is some progress from last year, when the Power were notoriously unable to beat teams in the top half of the ladder. But what they were able to do in 2017 was put away bad sides. Last season they had six wins by over ten goals – this year it has been none. Despite some decent recruits, the Power were probably a better team last year.

Port’s strengths: defence, and Robbie Gray

Port Adelaide’s defence in 2018 has been very good, with only Richmond having conceded less points. The Power currently lead the league in ‘one percenters’ (spoils mainly), with Dougal Howard recording the most of any player, and Tom Jonas near the top as well. Port has also conceded the least marks inside 50 of any team.

With Port though it is mainly a case of being decent, but not strong. Arguably they only have one ‘superstar’ at their position – the remarkable midfielder/forward Robbie Gray (maybe Paddy Ryder as well, when less hampered by injury). Gray got the Power over the line in the first Showdown this year with his six goals, and almost got them over the line with four goals in the other. Other than Gray they have a few pretty good players, including Ollie Wines, Justin Westhoff, Chad Wingard, and Travis Boak. It’s enough to keep them mid-range, but almost all of the top eight sides have more top-end talent than that.

The slither of hope: ‘do a Bulldogs’

In summary then Port Adelaide currently sitting in seventh is probably a fair reflection of their ‘true’ strength at the moment. Of course the ladder is so close that an upset win against Collingwood next week could considerably change the outlook for them. Otherwise though it looks like they will finish somewhere in the bottom rungs of the final eight, if they make it at all.

That actually puts them in a similar position to the Western Bulldogs when they won the premiership a couple of years ago. The Bulldogs’ amazing 2016 run though should be far from the preferred model for obtaining a premiership. More likely the Power will have an early exit, to be left wondering what else they can do to take the next step.

AFL Power Rankings: Round 20 2018

The AFL this year actually has a clear set of ‘bottom six’ teams. However, some of those teams are still much worse than the others.

With eighteen teams in the AFL, it’s somewhat natural for the league to think of the ladder as consisting of ‘three groups of six’.

This is what the AFL does in terms of determining its fixture each year. Teams in the ‘top six’ – based on last season’s finishing positions – will in theory have harder fixtures than those in the ‘middle six’ or ‘bottom six’ (though this doesn’t always work).

Potentially more significantly and controversially, under the AFL’s proposed ‘17-5’ fixture teams would be divided into ‘three groups of six’ after playing each other once in the first 17 rounds. The ‘top six’ teams would play for the top four spots in the final five rounds, the ‘middle six’ teams would play off for finals spots, and the ‘bottom six’ teams would play to determine who gets the highest draft picks.

Usually teams don’t fit neatly into groups of six in terms of ability. For example, last season Collingwood finished in the ‘bottom six’ in thirteenth position, and received a relatively easy fixture as a result. However, based on the Power Rankings Collingwood was an ‘average’ side that was about as good as the sixth-placed side, the West Coast Eagles. The Magpies and Eagles are among a bunch of ‘average’ sides that have taken the step up to being ‘good’ this season, but if you only consider ladder position the Pies’ rise seems more dramatic.

The ‘Dismal’ Six

This year though there has been a clear ‘bottom six’ sides – Fremantle, the Western Bulldogs, St. Kilda, Brisbane, Gold Coast, and Carlton. These six teams are all at least three wins behind every other team in 2018, with three rounds left. They are also clearly the six bottom-ranked sides, and have been since way back in Round 4.

The Lions have been OK recently

Nevertheless that does not mean these six teams are all about as equally ‘bad’. In particular the Brisbane Lions have been pretty good over the past few weeks (see first chart below). Indeed, despite currently sitting in sixteenth on the AFL ladder, the Rankings think the Lions are closer in ability to second-placed West Coast than seventeenth-placed Gold Coast! (See second chart below.)

The Lions are zero wins and five losses in matches decided by less than ten points so far this season. With at least a couple of wins in those close matches their ladder position would probably be a ‘fairer’ indication of their ability. On the bright side, with higher draft picks currently going to lower teams, they may end up with a higher draft pick than a team of their ability would usually get.

Gold Coast and Carlton are in depths of their own

Three of the remaining ‘bottom six’ sides – Fremantle, the Western Bulldogs, and St. Kilda – have been pretty ‘bad’, but not historically so. They have generally hovered around being three or four goals per game below average (see first chart above). They’re closer to Gold Coast than West Coast, but not by a huge amount.

Freo and the Bulldogs both have a couple of ‘stars’ holding them up – Nat Fyfe (until his injury) and Lachie Neale at the Dockers, and Marcus Bontempelli and Jack Macrae at the Doggies. The Saints have Jack Steven, and also a ‘rising star’ in young forward Jade Gresham. It’s not a great near-term outlook for any of them, but it’s not awful either.

Gold Coast and Carlton though are way below everyone else, as shown by them both losing by around 100 points on the weekend. They have generally been around six to seven goals per game worse than an average side (see first chart). Between them they have had 11 losses this year in excess of ten goals.

Carlton though at least has a genuine ‘star’ in Patrick Cripps, and a ‘rising star’ in Charlie Curnow. Gold Coast is going to lose one ‘star’ and co-captain this season in Tom Lynch (though they should receive good compensation), may lose the other in Steven May, and really do not appear to have much else in the way of ‘stars’ or ‘future stars’ in the near-term. Though the Suns are currently separated only by percentage from fellow Queensland side the Brisbane Lions, the gap between them may really be much, much larger.