In a month’s time the AFL
Women’s (AFLW) competition will kick off its third season. At the same time I
will start up the third season of my weekly
AFLW ‘Power Rankings’. These rankings aim to give a more accurate
reflection of the ‘current’ strength of each team than the ladder does. They
adjust each team’s results for the strength of its opponents, as well as
whether they played the match home or away.
For my rankings though the start
of the third AFLW season brings with it a new challenge. Two new teams will be
joining the competition – the Geelong Cats and the North Melbourne Tasmanian
Kangaroos. (Next
year will be even more challenging.) How should I rank these two
new clubs?
Initial
ranking points: look at the premiership odds
I faced this type of situation
before when I was trying to work out how to
initially rank the eight clubs in the AFLW’s first year. Back
then I decided the teams should not be rated as equal, since the ‘consensus’
view – as reflected in bookmakers’ premiership odds – was that they were quite
different in their ability.
This also looks
to be the case this year for Geelong and North Melbourne. North
Melbourne are rated as a very strong side, and have the second-lowest odds to
win the premiership, after last year’s premiers the Western Bulldogs. Meanwhile
Geelong are rated as a relatively weak side, with the longest odds to win the
flag.
Therefore I am going to start North Melbourne off on a relatively
high rating of about +5 points, which is
what the teams that were initially the highest ranked started on in 2017.
Conversely I will start Geelong on a
relatively low rating of about -7 points,
which is the same as the lowest ranked team at the beginning of 2017. (There is
a bit more behind my decision, but I don’t think the full method is either
interesting or ‘scientific’ enough to go into all of the specifics here.) All of the teams’ ranking points are also adjusted slightly, to keep the average number of
ranking points across teams at zero.
This will start North
Melbourne off in fourth spot on the rankings, and Geelong in second last. The
rankings update pretty quickly though because of the small number of matches,
with 25 per cent of a team’s ranking determined by its most recent
match alone. Hence a much better indication of the strength of these teams
should emerge within a couple of rounds of the new season, as it
did in 2017.
Home
ground advantage: think GWS
As there is only a small history
of AFLW matches to draw from, I base my adjustments for home ground advantage
(HGA) on the adjustments
I use for the men’s league (see table below). While I haven’t done a
big review of my men’s league HGA adjustments since those rankings began in
2010, they are still based on far more data than we have for the women’s league
to date.
In the men’s league I give Geelong the same HGAs as NSW teams against
Victorian clubs whenever the Cats are playing in Geelong. Therefore, my
HGA for the Cats in Geelong will be
based on that of GWS. Following this
rule and using my HGAs from last year would give Geelong an HGA of four points
when playing against Victorian or NSW teams in Geelong, and eight points when
playing against other clubs.
What to do for North Melbourne, which will play its
home games in Tasmania? In the men’s league my HGAs for Hawthorn and North
Melbourne when playing in Tasmania are smaller than their HGAs when playing in
Victoria, as they play less often there. That doesn’t seem right for a genuine
‘Tassie Kangaroos’ team though. Alternatively, I could give the Roos the same
HGAs as the other ‘Melbourne clubs’ – that is HGAs against non-Victorian teams
at home, but no HGAs against other Victorian teams.
However I’m going to take the
view that, since Tasmania is their permanent ‘home turf’, North’s HGA against
other Victorian teams in Tasmania should at least be as much as the Cats in
Geelong. After all, Victorian teams have to travel further to Tassie than they
do to Geelong. On the other hand, I don’t think I should make them any higher
than when Victorian teams travel to Sydney. Let’s make North Melbourne’s HGAs the same as Geelong’s and GWS’ then.
Note though that in the men’s
league I assume Geelong is not disadvantaged against Victorian teams when they
play at other Victorian venues. In AFL, Geelong plays a fair amount of games at
both the MCG and Docklands. In AFLW though that looks like it will not apply.
Therefore I will also add a disadvantage for the Cats (and Roos) when they play
elsewhere in Victoria.
One other thing – in general,
I’m not going to use the same HGAs as I have the first two years. When I first
came up with my women’s league HGA adjustments I didn’t know what the volume of
scoring would be. Given the scoring we
have seen so far, and since I am already making some adjustments to last
year’s rankings because of the new clubs, I am going to take this opportunity
to reduce them slightly.
In matches where GWS, Geelong,
and North Melbourne play the ‘Melbourne clubs’ I’m going to reduce the HGA from
four points to three points. In all other matches involving clubs from different
cities I’ll reduce the HGA from eight points to six points.
These new adjustments do not
make much difference to the ranking points, but seem more in line with the
scoring we’ve seen over the first two AFLW seasons (indeed, they may still be a
touch high). The table below lists the new HGAs, and compares them to the men’s
league.
Revised
rankings: Magpies now on top, but they are not the same team in 2019
As mentioned above, these
revisions make little difference to the rankings (see table below). Collingwood
regain the top spot it lost to the
Brisbane Lions after the Grand Final. The Lions’ showing in the GF
against the Dogs in Melbourne is now considered slightly less impressive with
the reduced HGA.
While the Pies’ top ranking
may seem peculiar given they only finished mid-table in 2018, it is because
they finished the year off really well. They had strong wins against Melbourne
and Adelaide, an away win against Brisbane, and a close loss against the
Bulldogs. Given that Collingwood is in the weaker half in the premiership odds,
maybe one should be thinking about the Magpies as a ‘good bet’ then?
Not so fast … what the
premiership odds likely reflect that the rankings do not is that Collingwood
lost some top players to North Melbourne, including Jess
Duffin, Jasmine Garner, Moana Hope, and Emma King. The
Magpies have also lost AFLW Rising Star winner Chloe Molloy for the season due to injury. Top-end
talent matters more in AFLW than the men’s league, and the forward prowess that
we saw from Collingwood in the second half of 2018 is likely to be
significantly curtailed this season.
Indeed you could make an
argument for a more significant shake-up of the rankings given the off-season
player movements. As I said above though, if these player movements do result
in large changes in performance the system will correct quite quickly. For the
most part the revised rankings are not too far off what ‘the market’ is saying
about how teams are expected to perform this season, so I’ll leave the tinkering
there.
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