The Fairness of the AFL Fixture

In yesterday’s post I rated the difficulty of each AFL team’s draw in 2015. Each year there is a fair bit of variation in the difficulty of the draw between teams; for example, in 2015 I consider the club with the easiest draw, West Coast, to have a goal a game advantage over the club with the hardest draw, Port Adelaide.

Over at the FootyMaths Institute it has been proposed that a fairer 2015 fixture would have each team play opponents of roughly the same level throughout the year. To achieve this it has been suggested splitting the teams into three conferences of roughly equal strength as follows, with each team playing the teams in their own conference twice and every other team once.

Conference 1: Teams ranked 1, 6, 7, 12, 13, 18.
Conference 2: 2, 5, 8, 11, 14, 17.
Conference 3: 3, 4, 9, 10, 15, 16.

That seems about as fair as you can get to me. (Ladder positions can be misleading of course, but I doubt the AFL is going to do a fixture based on a Power Rankings system!) A comment I made was that the conferences need only be notional; that is, teams could be split into conferences for the purposes of the fixture, but the ladder is calculated according to the same method as it always was.

Yesterday I wondered how far the actual AFL fixture deviated from this ‘fair’ system. To compare the two, let’s see how each team’s draw would be rated under the FootyMaths system. I am going to assume that the FootyMaths fixture would result in no net home ground advantage to any team over the course of the year. This probably will not strictly hold because of things like Geelong playing in Geelong against Melbourne clubs, but unless you get savaged like St. Kilda did for 2015, net home ground advantage is generally the least important component of a club’s fixture.

Here are the results:

	Overall	Effect of not playing own team	Effect of teams played twice
Sydney	78.0	33.8	44.2
Hawthorn	68.0	34.6	33.4
Port Adelaide	41.8	21.5	20.3
North Melbourne	28.8	9.2	19.6
Adelaide	24.2	16.7	7.5
Fremantle	21.9	15.6	6.3
Essendon	18.2	3.9	14.3
West Coast	17.5	13.4	4.1
Richmond	11.8	6.5	5.3
Geelong	4.8	7.1	-2.2
Carlton	1.3	-4.6	5.8
Gold Coast	-13.7	-12.0	-1.6
Collingwood	-26.5	-12.7	-13.8
Western Bulldogs	-42.7	-20.8	-21.9
GWS	-51.4	-21.0	-30.3
Brisbane	-54.2	-22.4	-31.7
Melbourne	-57.0	-27.9	-29.1
St. Kilda	-70.9	-40.7	-30.3

What the - ? This seems to be more uneven than the current AFL fixture! Note that the easiness of each’s team fixture is essentially determined by their ranking. Lower-ranked teams are now hit by a double whammy: not only are they the only team that do not get to play themselves when each team plays each other once, they are also the only team in their ‘conference’ that do not get to play themselves twice either.

We seem to have hit on something crucial here about what constitutes a ‘fair’ fixture. On one hand you could argue that the AFL should compensate for lower-ranked teams not being able to play themselves and give them easier teams to play to make up for it (although they seem to have overcompensated on this point). On the other hand you could argue that a ‘fair’ system should abstract from this effect.

Note here that a ‘fair’ fixture could result in teams having draws of varying difficulty. Perhaps Sydney and Hawthorn might have the easiest draws under the FootyMaths system because they do not have to play themselves, but this does not necessarily mean that the fixture is not ‘fair’.

What happens if we take out the effect of not having to play your own team? (I have also taken out the net home ground advantage from the AFL fixture as well.)

	FMI fixture	AFL fixture
Gold Coast	10.4	-8.4
North Melbourne	10.4	-19.7
Essendon	10.4	-0.8
Carlton	10.4	19.7
Sydney	10.4	-63.8
St. Kilda	10.4	93.2
Hawthorn	-1.1	-96.2
Port Adelaide	-1.1	-101.4
Collingwood	-1.1	27.7
Richmond	-1.1	-17.9
Western Bulldogs	-1.1	77.0
Melbourne	-1.1	107.5
GWS	-9.3	72.5
Fremantle	-9.3	-38.1
Geelong	-9.3	-88.7
Adelaide	-9.3	-24.2
West Coast	-9.3	27.8
Brisbane	-9.3	33.9
Standard deviation	8.3	63.6

Now that seems better. Basically the difference between the hardest ‘conference’ and the easiest one is less than a point a game. For the AFL fixture the difference between the hardest draw and the easiest one is about two goals a game.

Personally I like the FootyMaths proposal; it seems to me about as fair as you can get with each team playing 22 matches. It might be even better than having a 17 round season.