Simulating the Finals for 2016 After Week 2

It seems a bit grandiose to dub the work summarised in this blog as a "simulation" since, with just three games to go, all that's been required to assemble it has been six probability assumptions: two for the Preliminary Finals and four for the possible Grand Final matchups.

As far as MoSSBODS is concerned, those probabilities are as per the table at right.

Some of the entries in this table might, at first, seem perplexing - why, for example, do the Dogs start as slight favourites over the Swans? To understand why this is the case we need to recall the Travel Penalty that MoSSBODS imposes on all teams playing a match out of their home State against an opponent in its home State. 

That 3 Scoring Shot penalty is relevant for both of this week's games as well as for the possible Geelong v GWS, and Sydney v Western Bulldogs Grand Finals where the two Sydney-based teams would incur the Penalty.

Whether or not that imposition should apply in Finals is an interesting (and ultimately empirical) question, and one I'll be explicitly considering in the off-season as I develop a challenger for the MoSSBODS Rating System. 

For now though, we're stuck with it. We can get a sense of how relatively important it is by breaking down the components of MoSSBODS' net ratings for each matchup, which I've done in the table at left.

The top section provides details for each of the teams' Combined Rating, as well as their Venue Performance values for the relevant grounds. The bottom section uses these values, plus the Travel Penalty where applicable, to come up with net ratings for the Preliminary Finals and the four possible Grand Finals.

Geelong is shown as a 3.5 Scoring Shot (SS) favourite against Sydney at the MCG, for example, based on the following calculation: 

(Geelong Combined Rating + Geelong Venue Performance at the MCG) LESS (Sydney Combined Rating + Sydney Venue Performance) at the MCG PLUS Sydney Travel Penalty.

In numerical terms, that is: (6.4 + 0.7) - (6.9 - 0.3) +3 = +3.5 SS

Geelong, we can see, would still be favourites,but only by 0.5 SS, if not for the Travel Penalty.

The figures for the other matchups can be calculated in a similar fashion and reveal that the Dogs' putative favouritism over the Swans in the Grand Final comes solely from the Travel Penalty. Without it, the Dogs would start as 2.3 SS or about 8 point underdogs.


So, if we apply the game probabilities just described, we obtain the Flag probabilities shown in the table at right.

Compared to the current TAB market, these rate the Cats' chances more highly and the Giants', Swans' and Dogs' less highly. In fact, at the TAB price of $3, the Cats represent significant value if their true Flag chances are 40%.

Lastly, we can also look at the probabilities for the four potential Grand Final pairings, which we do in the table at left.

It suggests that there's almost a 50% chance that the Cats will meet the Giants in October, making this pairing, at $2.39, the only one currently offering any value on the TAB.