2021 : Simulating the Finals before Week 2

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Today we take a look at a MoSHBODS-based simulation of the remaining five games of the Finals.

METHODOLOGY

As noted last week, broadly speaking the simulations of the Finals use the same methodology that was used in the simulations of the home-and-away season, including the manner in which home ground advantage is estimated.

Home Ground Advantage estimates or, in MoSHBODS’ terms, Venue Performance Values (VPVs), are handled a little differently in Finals than they are in home-and-away games in that multipliers are applied to them as follows

  • In Finals other than the Grand Final played in a team’s home state, the same VPVs are used as would have been the case if the game were played in the home-and-away season

  • In Finals other than the Grand Final played in other than a team’s home state, the VPVs are doubled

  • In Grand Finals, the VPVs are multiplied by 0.25

To know which VPVs to use, we need to make some assumptions about where the Semi-Finals, Preliminary Finals, and Grand Final will be played. We know that, COVID-permitting:

  • Semi-Final 1 will be played at the Gabba

  • Semi-Final 2 will be played at Perth Stadium

  • Preliminary Final 1 will be played at Perth Stadium

  • Preliminary Final 2 will be played at the Adelaide Oval

There is still conjecture about where the Grand Final will be played but, for this run, I’ve assumed it’ll be played at the MCG. Call me an optimist.

RESULTS

In this first chart we simply look at the estimated probabilities for each of the 8 Finalists going out in a particular week of the Finals.

The simulations continue to highly value the double-chance and we see that the Top 4 teams provide the Grand Finalists in the vast majority of replicates. Outside the Top 4, the Bulldogs make the Grand Final about 8% of the time, and GWS about 9%.

Melbourne are now rated about 4-in-10 chances for the Flag, Port Adelaide 3-in-10, Geelong 1-in-8, and Brisbane Lions 1-in-10. GWS and Western Bulldogs are both about 1-in-33 chances.

Drilling down a level on the 50,000 replicates, we can analyse the paths to elimination followed by each team, and these are summarised in the chart below.

One interesting thing to note from this is that Melbourne are the only team more likely to win than lose a Grand Final, should they get there. Geelong are, overall, roughly equally as likely to win it as to lose it.

Lastly, let’s look at what the replicates reveal about possible Grand Final matchups.

We see that a Port Adelaide v Melbourne Grand Final is the most common pairing, accounting for about 9-in-20 of all replicates. Melbourne wins just over 60% of the time.

Next most-common is a Melbourne v Brisbane Lions Grand Final, which also appears in about 3-in-20 of all replicates, with Melbourne winning just over 60% of them as well.

Geelong v Port Adelaide accounts for another 1-in-6 replicates, Port Adelaide v GWS 1-in-16, and Brisbane Lions v Geelong, and Melbourne v Western Bulldogs about 1-in-18 each.

Altogether, Grand Finals involving any two of the Top 4 teams account for about 84% of all Flag winners.

UPDATE : WEDNESDAY PM

Since we now know* that the Grand Final will be played at Perth Stadium, we can update these simulations for that fact.

The results are below, and reveal that:

  • Melbourne’s probability of winning the Grand Final, given that they make it, drops by about 1% point to just over 61%

  • Geelong’s probability of winning the Grand Final, given that they make it, drops by about 2% points to just over 48%

  • Port Adelaide’s probability of winning the Grand Final, given that they make it, increases by about 1% point to just under 44%

  • Brisbane Lions’ probability of winning the Grand Final, given that they make it, increases by about 2.5% points to just under 45%

With the switch from the MCG to Perth Stadium, that seems reasonable.

* for suitable values of the term “know” during a global pandemic