AFL Finals: Week 1 Predictions

Here we go, we need to make our predictions for the finals.

And there will be a few statistics in here, so stay tuned.

Footy Maths Institute, which you should really read if you don’t already, has made a chart showing the win-loss record of teams in the finals against each other.

TOP 8 SIDES AGAINST EACH OTHER 2015
TEAM PL W D L F A PTS % MR
1 Hawthorn 8 6 0 2 842 529 24 159.2 0.75
2 W Bulldogs/FFC 8 5 0 3 710 757 20 93.8 0.63
3 Fremantle 10 6 0 4 827 816 24 101.3 0.60
4 West Coast 10 5 0 5 992 884 20 112.2 0.50
5 Richmond 9 4 0 5 711 721 16 98.6 0.44
6 Sydney/SMFC 8 3 0 5 599 704 12 85.1 0.38
7 Adelaide 8 3 0 5 719 755 12 95.2 0.38
8 North Melbourne 9 3 0 6 678 912 12 74.3 0.33

Firstly, how good are the Bulldogs?

Secondly, we can use this to gather some datapoints.

  • West Coast v Hawthorn: +0.25 Hawthorn
  • Fremantle v Sydney: +0.22 Fremantle
  • W Bulldogs v Adelaide: +0.25 W Bulldogs
  • Richmond v N Melbourne: +0.11 Richmond

This matches up with my original, pre-analysis predictions. A second datapoint to add is a team’s record at home and away from home, compared to their overall record.

Team Games Wins % Home/Away Wins % Difference
Fremantle Home 22 17 0.77 9 0.82 0.0454545
West Coast Home 22 16.5 0.75 9 0.82 0.0681818
Hawthorn Away 22 16 0.73 8 0.73 0
Sydney Away 22 16 0.73 8 0.73 0
Richmond Home 22 15 0.68 6 0.55 -0.1363636
W Bulldogs Away 22 14 0.64 5 0.45 -0.1818182
Adelaide Away 21 13 0.62 6 0.55 -0.0735931
N Melbourne Away 22 13 0.59 6 0.55 -0.0454545

I’m classing this as an away game for the Bulldogs, as our home games are at Etihad Stadium rather than the MCG. (I’m not going to let go of that anytime soon.)

Combining the two figures, we end up with this:

Game Home Sum Away Sum Home team difference Winner
WCE v HAW West Coast -0.18 Hawthorn 0.25 -0.43 HAWTHORN
FREM v SYD Fremantle 0.27 Sydney -0.22 0.49 FREMANTLE
WB v ADEL W Bulldogs 0.07 Adelaide -0.32 0.39 W BULLDOGS
RICH v NM Richmond -0.03 N Melbourne -0.16 0.13 RICHMOND

That’s all well and good, but we also need to compensate for recent form.

Basing it on team’s past 10 games, and getting +0.05 for a win and -0.05 for a loss, each of the teams ends up with:

  • Fremantle: +0.10
  • West Coast: +0.25
  • Hawthorn: +0.30
  • Sydney: +0.20
  • Richmond: +0.30
  • W Bulldogs: +0.20
  • Adelaide: +0.20
  • N Melbourne: +0.20

The new, slightly revised statistics:

Game Home Sum Away Sum Home team difference Winner
WCE v HAW West Coast 0.07 Hawthorn 0.55 -0.48 HAWTHORN
FREM v SYD Fremantle 0.37 Sydney -0.02 0.39 FREMANTLE
WB v ADEL W Bulldogs 0.27 Adelaide -0.12 0.39 W BULLDOGS
RICH v NM Richmond 0.27 N Melbourne 0.04 0.23 RICHMOND

Still the same results. Another thing we need to take into account is form against the other club Teams earn +0.1 for a win and -0.1. For example, if two random teams, say Alexandra and Bendigo, had played each other five times, Alexandra had won 3 and Bendigo 2, then we’d have Alexandra on +0.1 and Bendigo on -0.1. And for each of the matches:

  • West Coast v Hawthorn: Hawthorn +0.5, West Coast -0.5.
  • Fremantle v Sydney: Fremantle 0, Sydney 0
  • W Bulldogs v Adelaide: W Bulldogs -0.1, Adelaide +0.1
  • Richmond v N Melbourne: Richmond -0.3, N Melbourne +0.3

The updated table:

Game Home Sum Away Sum Home team difference Winner
WCE v HAW West Coast -0.43 Hawthorn 1.05 -1.48 HAWTHORN
FREM v SYD Fremantle 0.37 Sydney -0.02 0.39 FREMANTLE
WB v ADEL W Bulldogs 0.17 Adelaide -0.02 0.19 W BULLDOGS
RICH v NM Richmond -0.03 N Melbourne 0.34 -0.37 N MELBOURNE

That’s been enough to overturn the Richmond-N Melbourne result. A final variable that needs to be taken account of is finals experience. So, teams will get +0.05 for each year since 2011 they’ve made the finals.

  • Fremantle: +0.15
  • West Coast: +0.1
  • Hawthorn: +0.2
  • Sydney: +0.2
  • Richmond: +0.15
  • W Bulldogs: 0
  • Adelaide: +0.05
  • N Melbourne: +0.1

And that leads to our final predictions:

Game Home Sum Away Sum Home team difference Winner
WCE v HAW West Coast -0.33 Hawthorn 1.25 -1.58 HAWTHORN
FREM v SYD Fremantle 0.52 Sydney 0.18 0.34 FREMANTLE
WB v ADEL W Bulldogs 0.17 Adelaide 0.03 0.14 W BULLDOGS
RICH v NM Richmond 0.12 N Melbourne 0.44 -0.32 N MELBOURNE

The closest game is to be Bulldogs v Adelaide. So, the teams that will win are Hawthorn, Fremantle, the Bulldogs, and North Melbourne.

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