Sunday, July 23, 2017

AFL Power Rankings: Round 18 2017

In the early rounds of 2017 two powerhouses of recent years – Sydney and Hawthorn – were falling fast. Both lost around three goals worth of ranking points over just the first five rounds of 2017.
But over the past five weeks they have been the two best performed sides in the competition. Based only on their past five weeks Sydney and Hawthorn would both be at around 30 ranking points, better than current top team Adelaide.
There isn’t much more of a point I’m making here other than credit where it is due: the Swans and the Hawks came back.

Sunday, July 9, 2017

AFL Power Rankings: Round 16 2017

Earlier in the week The Arc did a post on how much past seasons affect its current AFL ratings. There were a few teams that were notably affected by their performances in past seasons, but in general by this stage of the season it’s the current season that primarily matters. This gave me an idea though:
Working out the effect of past seasons in my rankings is pretty easy. My rankings are just based on a team’s past 22 matches, with more recent matches given more weight. Only the current and previous season matter and, unlike The Arc’s ratings and some other rating systems, teams do not regress towards the average between seasons – Round 1 in the current season just carries on from a team’s last game in the previous one.
The weights given to the previous season’s matches go down during the year. After one round into the season they are still up at about 91 per cent of the total, but after Round 5 they are down to about 60 per cent, after Round 9 they are about 36 per cent, and currently – after Round 16 – they are down to just 11 per cent.
Hence, as you can see from the table below, last season’s matches don’t matter much by this stage of the season. No team gains or loses more than about five ranking points from its results in 2016. Essendon, not surprisingly, is held back a bit by its weak, personnel-affected performances last year. Last year’s grand finalists – Sydney and the Western Bulldogs – are held up a bit by their strong performances in last year's finals series.

An interesting case is Sydney, which as The Arc noted were a top team in 2016 but has performed less well in 2017, particularly early in the season. As you can see in the graph below, when the Swans performed badly at the start of the 2017 their ranking points dropped fairly consistently from round to round as last season’s accumulated points fell away.
However, after Round 7 Sydney’s ranking points have been stable, as its improvement in this season has offset its loss of points from 2016. The result is that the Swans are still among the better teams even without last season’s performances holding them up.

Sunday, July 2, 2017

AFL Power Rankings: Round 15 2017

Richmond takes Essendon’s spot in the top eight of these rankings this week. The Tigers had a win over Port in Adelaide, while Essendon lost at home to bottom-ranked Brisbane. It is the first time Richmond has been in the top eight of the rankings since Round 4 of last season.

The Tigers have been consistent across matches this season rather than brilliant in a few. The win against Port Adelaide rates here as their best for the year, with a net margin adjusted for home ground advantage and opposition strength of +41 points. Only the bottom three ranked sides – Carlton, Fremantle, and Brisbane – have a ‘best adjusted net margin’ result for 2017 that is lower than Richmond’s, and Richmond only passed two of those sides with the win against Port this week.

But Richmond has been pretty consistent in its performances. It has the lowest variation (standard deviation) in adjusted net margin across its matches of any side this season, at +23 points. Its worst result this year, in adjusted net margin terms, was its 2 point loss to Fremantle at home (-43 points in adjusted net margin).

In other words, in this even season, Richmond’s season has been the most even of all.

Sunday, June 25, 2017

AFL Power Rankings: Round 14 2017

In keeping with a major theme of this season that teams that look like they are moving ahead will soon put in a bad performance, Adelaide marked its clear break at the top of the rankings by losing at home this week to lowly-ranked Hawthorn. The Crows still keep top spot in these rankings for now, but Port Adelaide and GWS now look about just as good.
Also showing the even nature of this season is that it doesn’t take much for the teams in the middle to move around a few spots in the rankings. Essendon moves up from tenth to eighth after the narrowest of losses in Sydney, Richmond moves up from twelfth to tenth, Collingwood drops from ninth to twelfth, and Geelong drops from third to fifth after squeaking home against Fremantle.
After three narrow wins this season Fremantle’s luck in close games ran out against the Cats. (As a Richmond supporter I wish Freo’s missed shot at goal near the siren had come against us.) Those narrow wins have been keeping the Dockers much further up on the ladder than they are rated here.
Melbourne’s rating moves a little higher still after its exciting win in Perth against the West Coast Eagles. The Demons are rated as basically as strong as fourth-ranked Sydney and fifth-ranked Geelong. Can they become an actual top-four ranked team – and actual top four ladder team – with a win against the Sydney Swans next week?

Sunday, June 18, 2017

AFL Power Rankings: Round 13 2017

End of the ‘bye’ rounds – the mid-season wasteland in the AFL schedule when the football feels very cold, blank, and June-ish. Except the vacant match slots haven’t seemed to have felt as pronounced as previous years. Perhaps it is because of the relatively even nature of the season, with only two wins (OK, effectively three wins given percentage) separating fourth (Port) from fifteenth (Carlton) on the ladder. Teams down the bottom of the ladder have about a one-in-five chance of making the finals – enough to keep the optimistic hopes of fans alight, rather than have them virtually extinguished.
One club which has usually had its hopes already extinguished in recent years is Melbourne, who is now enjoying its highest-ever rankings spot (sixth). Stretches of years at the bottom are meant to yield high draft picks and the best young players to help get a team back up the ladder again. But Melbourne’s stint at the bottom from 2007 to 2010 yielded few long-term players – let alone long-term stars – with Morton (‘07), Grimes (‘07), Scully (‘09), Trengove (‘09), Gysberts (‘09), and Cook (‘10), all gone or virtually gone from the club for one reason or another. At this point the Demons look to be getting good production out of their next generation of high picks (in particular Clayton Oliver), complemented by solid pick-ups from other clubs. More proof that, in the modern AFL system, a team won’t stay down the bottom for years on end.     
Meanwhile, the Demons’ victims on the weekend – the Western Bulldogs – seem to be reverting back to the level they were at before that magical run in the 2016 finals series. As predicted on this blog as early as Round 1 this year (I only highlight the predictions that come true), comments have come about the Bulldogs being ‘off the boil’, even though they are playing at around the same level as they did for most of last year. It’s true that they have dropped off a bit more in the past couple of weeks, but the Bulldogs not being among the top clubs to date in 2017 was not the hardest thing to predict this season.

Monday, June 12, 2017

AFL Power Rankings: Round 12 2017

It seemed likely that, with Essendon getting its full team back this year following the bans from the World Anti-Doping Agency, that ranking systems would underrate the Bombers coming into 2017. What was less predictable though was that Essendon would suddenly start performing like an elite side over the past five weeks. The Dons have gained a whopping 25 ranking points following huge wins against Port Adelaide and West Coast, a win against highly-rated Geelong, and a small loss to GWS on the road (a loss to Richmond was their other result). As a result the Bombers jumped this week from thirteenth to tenth in the rankings, and are less than a point away from positive rankings territory.
Staying in that region of the rankings this week Melbourne and Collingwood fought it out for eighth spot in the rankings, and for a spot in the eight on the actual AFL ladder. Melbourne narrowly won both, in one of the better matches for the season. Can the Demons continue their rise next week against the Bulldogs?
Meanwhile the unpredictability continues amongst the league’s top-ranked sides. Port Adelaide’s big loss to Essendon, and GWS’ loss to lowly-rated Carlton, has given Adelaide a clear break at the top of the rankings – at least until the Crows’ next big upset loss …

Sunday, June 4, 2017

AFL Power Rankings: Round 11 2017

There’s not much happening in the rankings this week, with one-third of the league having the week off. (Under my system teams can still change ranking points even when not playing, as the strength of their recent opponents is revised.)
The gap between the Adelaide Crows and Port Adelaide at the top of the rankings has narrowed, with the two clubs now rated about the same, while Geelong has crept closer to the top sides with its comfortable win over the Crows.
West Coast has fallen further into the ‘mid-range’ group of the rankings after losing to the lowly-ranked Gold Coast Suns. Conversely, Essendon has moved closer to that group with a decent performance on the road against the GWS Giants.
And Richmond has almost made the long road back into positive rankings territory. Only their three thrashings against the Swans, Giants, and Hawks in the second half of last year are keeping the Tigers out of seventh spot.