Monday, 3 November 2014

Fixture - Correct Weight?

As is the flavour of the moment, we turn our attention to the 2015 fixture issued by the AFL, and assess 'who got the tough one'.

Its an annual thing, now in its fourth fabulous season*, and very much due for a ringing celebrity endorsement (Oh, I dont know... maybe of the Coach Ronnie value?).

*Past assessments here: 2014, 2013, 2012.

The AFL Fixture.

The fixture is in and released on 30 October, and fully available here [PDF]
For season 2015, the AFL attempted a new determination of the fixture - a selection of teams to play inside groups based on ladder positions.

The "weighted rule" will be in effect again, with each club to play every other club once and five clubs twice.
This is done in accordance with last year's ladder, with the clubs grouped into top six, middle and bottom teams to manage the equality of the double match-ups.
 "We're happy with the way it works. I think if you look at it, all the right teams are playing each other in our view," said Simon Lethlean, the AFL's general manager of broadcasting and scheduling.
McLachlan denied it was a "handicap" format.
"In an imperfect world, which our fixture is and we've acknowledged that for many years, you're playing at the margins and all we've done is actually get some slight weighting going into who plays who twice," McLachlan said.

Sort of a 'weighted rule', but really a handicap. Hell, even Stevo can see that!

Given it is a 'handicapping', at least it is not the outright gerrymandering we have seen in the past. At least now there is some semblance of structure to fixing the fixture.
One again, Stevo with the detail (IKR!!!).

Which is a really handy picture, because it lays out the structure for the fixture in a simple easy to read format.
And it also shows that the AFL have also left themselves enough wriggle room to schedule up games according to ground availability etc. Which is a handy way of saying 'we will schedule what ever we want'.

Those 'maximum' / 'minimum' quotas are there just so they AFL can still fit in a double-up on Derbies, Showdowns and Melbourne blockbusters.

Its a handy way of scheduling to look like your doing the right thing, but not really so as not to upset the status quo and those who benefit from it.

If the AFL were fair dinkum about competitive balance and equalisation, they don't need to go full-on conferences, but an even more scaled down version where each team plays others ranked similarly.

But back to 'who got dudded'.

Assessments of the Fixture:

We have run the assessment based on our numbers below, but it is worth pointing out firstly that:

Troy Wheatley has also assessed the fixture using his rankings, and has blogged them thus.
Interestingly he defines Port Adelaide with the toughest draw (followed by Geelong, Hawthorn, and (oddly) Gold Coast).
At the top of Troys table (the soft end of the draw) he calculates West Coast getting the best run of it (?!?) followed by Melbourne, the Western Bulldogs and GWS.

Now, this does not align neatly with what the AFL are trying to do so much (i.e. stronger teams get a harder draw, etc), as evidenced by the Suns bobbing up in 4th (and the Saints and Magpies in 6th and 7th).

Troy goes on in another blog post to consider our proposal (that teams should play against others ranked similarly) and determined that
"the FootyMaths proposal ...seems to me about as fair as you can get with each team playing 22 matches"
Gotta be happy about that.

As always Rohan Connolly at The Age has assessed the fixture using the (soon to be patented, no doubt) 'Connolly Method', as below.

This method, as the detail at the top points out used the AFL ladder position along with the fundamentals of the fixture (including days break, travel etc) to award points to each team, and then rank them.

Under this system, the teams 'Play Twice' numbers tally up to show that the top 8 from last year fit into
the top 10 'toughest fixture' ranking. Joining them are Adelaide (51pts, ranking in 6th) and Collingwood - equal 9th/10th with Essendon.

Once the 'Road Trips', '6 Day Breaks' and 'Home vs Interstate' mix data is added, Collingwood slip down the difficulty scale, leaving the top 8 filling the 9 slots for hardest draw. Again, Adelaide are nosing their way in.

The nett effect of the 'Connolly Method' is that pretty much is in alignment with what the AFL are after... namely that the stronger teams get a harder run, and the poorer performers have a slightly easier time of it.

There are limited anomalies in the above table... only the positioning of Adelaide (10th) in the 'toughest 8', and the West Coast (9th) making out like bandits with the 5th easiest draw.

Using the FootyMaths rankings, we have also calculated our assessment of the fixture.
The table below considers the opposition strength, home/away bias, and
- quality of the opposition,
- expectations of a 'win' for each game,
- an expected end of year rank
- an expected end of season ranking for a perfectly even draw, and the
- difference between those two ranking weights.
The table below is the results, with the top of the table teams having the harder draws.

1Port Adelaide513152345806.61
5North Melbourne61226231022004.50
10West Coast9120323028-1002.96
12Brisbane Lions15874234681000.82
14Gold Coast1298922905-200-0.83
16W Bulldogs/FFC1490922908-100-1.99
18St Kilda1870322710100-2.37

In calculating these numbers we find that (based on or ranking numbers) the AFL had gone very close to achieving its 'handicapped' fixture.
The top 8 teams of the ladder are all in relative close proximity to their 'tough draw index' position, and there is also great alignment at the bottom of the spectrum too.

Looking at the above, its possible to think Port Adelaide suffer the most (+4 from their ladder position), with Brisbane also similarly affected (+3).

A range of teams have marginally benefited (-2), and these are Fremantle, Sydney, Gold Coast and Western Bulldogs.

But all in all, it looks like the AFL have achieved their outcome, so ... well done!

Its almost as if they are using our data and methodology to work up the fixture outcome... well we can dream anyway.
If only they would try a non-handicapped approach... maybe for 2016?

Tuesday, 21 October 2014

The Fixture Countdown

There are only 9 more days until the AFL once again dominates the media landscape with the release of the fixture for 2015 (scheduled Oct 30... 5 days before some sort of a horse race, apparently).

Which of course means all the journos will be writing and tweeting about 'who got the best draw' and '[club] always gets a soft draw' and of course [club that never leaves the MCG] travels the least'.

If the AFL is to follow its proposed plan, we should see the schedule aligned so that the top teams of 2014 (Hawthorn, Sydney, Fremantle, Geelong, Port Adelaide and North Melbourne) play each other twice.
Those not so brilliant in 2014 are also proposed to play each other twice (Carlton, the Bulldogs, Brisbane, GWS, Melbourne and St Kilda), and the middle 6 also dance about twide too.

This is being pitched as producing a fairer result for teams, in that it will reduce blow-outs etc, as well as maintain interest in the season.

While having the previous seasons cellar dwellers not play powerhouses twice, but instead play among them selves looks fairer (on the day at least) it is entirely not a fair fixture. To be properly fair, each team should play against the same level of opponents every year. Ultimately, this is best achieved by the old 'play each other home and away twice' rule. But that is totally impractical in an 18 team competition.

Regular readers will know that we have proposed a [lengthy] scenario that is fair and transparent, and has teams play against similarly weighted opponents home and away (and against all others once) in a three conference system.

The key component is not the introduction of conferences, but the distribution on teams that competitors paly against. As Troy Wheatley correctly points out in the comments on our previous post, the fairness factor in the model doesn't need the conference element.

A fair 2015 fixture would involve home and away games played between the teams in the three columns below, with additional games played against teams outside of that alignment.
6North Melbourne5Port Adelaide4Fremantle
7Essendon8Richmond9West Coast
12Gold Coast11Collingwood10Adelaide
13Carlton14W Bulldogs/FFC15Brisbane Lions
18St Kilda17Melbourne16GWS

Also as mentioned previously, this is an unusual allotment, given Geelong is the only Vic-based team n the last column. It therefore travels interstate 5 times.
This now becomes the benchmark for the future - all Vic-based teams should travel 5 times interstate.

So looking at the above, and taking a few teams at random, lets look at where those teams play.
First Geelong:
9West Coast5Port Adelaide9West Coast6North Melbourne
15Brisbane Lions12Gold Coast15Brisbane Lions11Collingwood
16GWS13Carlton16GWS14W Bulldogs/FFC
18St Kilda17Melbourne

The above shows a POSSIBLE fixture scenario. There are 11 home and 11 away games, with 5 of those away games interstate for this Vic-based club (italicized for easy reference). Also split such that the teams played twice are in the left column of each home/ away list.

Also, to round out the distribution, if you tally all the numbers under home or away, you get 111 (each of two)... so the level of competition Geelong faces home and away is the same.

And we can run scenarios for other teams in Victoria, along the same lines too.
St Kilda:
St Kilda
6North Melbourne5Port Adelaide6North Melbourne4Fremantle
7Essendon8Richmond7Essendon9West Coast
12Gold Coast11Collingwood12Gold Coast10Adelaide
13Carlton15Brisbane Lions13Carlton14W Bulldogs/FFC

Again, 5 interstate trips as italicized, and 11 home games. Again the numbers under under home or away tally up to be 96 in both. Balanced scheduling.
(yeah that 96 is different to the 111 for Geelong as obviously the teams own ranks are different).

And finally, lets look at Collingwood and give them 5 interstate journeys.
5Port Adelaide3Geelong5Port Adelaide6North Melbourne
8Richmond7Essendon8Richmond9West Coast
14W Bulldogs/FFC12Gold Coast14W Bulldogs/FFC10Adelaide
18St Kilda15Brisbane Lions

A neat 5 trips away to foreign lands to spread the Magpie love, and the balance in the schedule of all the numbers adding up to 103 in both home and away columns.

Now these three random selections were just plucked out and determined last night. It may not always work that you can balance out the numbers so well, but in this instance it is a good result.

And in the end... isn't that what the AFL should be striving for? 
Balance among teams and how they play.