Matter of Stats

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2022 : Simulating the Finals Series After Round 19

With just a month’s worth of football to go now until the Finals, let’s take a look at the latest set of simulations for those Finals.

(For details about the methodology, see this blog post and also refer to this one from last week that talks about an alternative approach to adding time-based variability to team ratings that I’m currently trialling)

Applying the “traditional” methodology to 10,000 of the 50,000 home and away season simulation replicates yields the following chart showing teams’ Finals fate overall and as a function of their ultimate ladder position at the end of the home and away season.

Overall, we see that the teams fall fairly naturally into seven groups:

  • Geelong: just over 1-in-4 chances for the Flag and just over 4-in-9 chances to make the Grand Final

  • Melbourne and Sydney: just over 1-in-6 chances for the Flag and just under1-in-3 chances to make the Grand Final

  • Brisbane Lions and Fremantle: about 1-in-8 to 1-in-10 chances for the Flag and just over 2-in-9 to 1-in-4 chances to make the Grand Final

  • Collingwood and Carlton: about 1-in-16 chances for the Flag and just under 1-in-8 to 1-in-6 chances to make the Grand Final

  • Western Bulldogs: about 1-in-33 chances for the Flag and 3-in-50 chances to make the Grand Final

  • Richmond: about 1-in-100 chances for the Flag and 1-in-50 chances to make the Grand Final (and about 1-in-4 chances of even making Finals)

  • St Kilda: about 1-in-200 chances for the Flag and 3-in-200 chances to make the Grand Final (and about 1-in-5 chances of even making Finals)

  • The Rest: unlikely to make the Finals

We also can see that Geelong, Melbourne and Sydney are the only teams that win more than 50% of the Grand Finals that they make.

WEEK OF ELIMINATION IN FINALS

In this next chart we look at teams' chances for various Finals finishes, ignoring their home and away ladder positions (ie we focus solely on the heights of the bars in the previous chart). The numbers shown inside a cell are the percentage of simulation replicates (multiplied by 100) in which the specified team went out in the specified week of the Finals.

We see here that, if we define the season in terms of the five events listed above plus "Miss the Finals", the most-likely finishes for each team are estimated to be:

  • Lose in a Preliminary Final: Geelong, Melbourne, Sydney, and Brisbane Lions. But note that Geelong, Melbourne, and Sydney are all more likely to make the Grand Final than to lose in a Preliminary Final

  • Lose in a Semi Final: Fremantle

  • Lose in an Elimination Final: Collingwood, Carlton, and Western Bulldogs

  • Miss the Finals: all other teams

GRAND FINAL PAIRINGS 

In this final chart we look at all of the Grand Final pairings that occurred in at least one of the simulation replicates. The numbers shown inside a cell are the percentage of simulation replicates (multiplied by 100) in which the team named in the row defeated the team named in the column in the Grand Final.

We see that the most common Grand Final, again, has Geelong defeating Melbourne. This occurred in 5.5% of replicates. The opposite result - Melbourne defeating Geelong - occurred in another 4.7% of replicates. A Geelong v Sydney Grand Final is the next most likely, occurring in about 10% of replicates. Geelong v Brisbane Lions is next at around 8%, then Geelong v Fremantle at around 7%.

(Note that zeroes in the chart represent pairings that did occur at least once but in less than 0.05% of replicates.)

CHARTS FOR THE ALTERNATIVE METHOD

Applying the alternative methodology (see this post for details) to both the home and away season simulations and then to 10,000 of those for the purposes of simulating the Finals yields the following, alternative outputs.

As we’ve seen each week in the comparison, this methodology tends to improves the results for strong teams, because it introduces less variability into the ratings used for games in the more distant future. Here that benefits Geelong and Sydney.

Overall, the team-by-team main differences are:

  • Geelong’s Flag chances increase from about 27% to 36%

  • Melbourne’s Flag chances remain at about 16%

  • Sydney’s Flag chances increase from about 17% to 19%

  • Brisbane Lions’ Flag chances decrease from about 12% to 10%

  • Fremantle’s Flag chances decrease from about 10% to 7%

  • Collingwood’s Flag chances decrease from about 7% to 4%

  • Carlton’s Flag chances decrease from about 6% to 4%

  • Richmond ’s Flag chances decrease from about 1% to 0.5%

  • St Kilda’s Flag chances decrease from about 0.5% to 0.1%

For completeness’ sake, here are the Grand Final matchup numbers under this alternative methodology:

The Melbourne v Geelong Grand Final now turns up in 14% of replicates, which is almost half as much again as under the earlier methodology. Geelong v Sydney is now the most-likely Grand Final pairing, and appears in 16% of replicates, with Geelong v Brisbane Lions in third at just over 9% of replicates.