Matter of Stats

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2019 : Simulating the Finals Series After Round 22

Last weekend’s results had quite an impact on the likely shape of the Final 8, and also some impact on the race for the Flag as reflected in the latest simulations of the Final series using the methodology described here and the 50,000 final home-and-away ladders produced by our original simulations.

The results are summarised in the chart below, which shows each team’s Finals fate in terms of where they finished on the ladder at the end of the home-and-away season.

(Again, note that the bottom half of the chart is a mirror of the top half, but with each team enjoying its own y-axis in the bottom half to improve the ability to discern their underlying percentages.)

The four teams that are still most likely to win the Flag are Richmond, Geelong, Brisbane Lions, and West Coast, and and it is still also the case that Geelong and Richmond (and Collingwood) are better than 50% chances should they make the Grand Final, and Brisbane Lions and West Coast both slightly worse than 50% chances should they make it.

Across the 50k replicates, 11 teams still make the Finals at least once, and all of them go as far as securing the Flag in at least one replicate.

Summing across the teams, we have now the following analysis of Grand Final success based on final home-and-away ladder position:

  • 1st or 2nd wins 42% of the time, and finishes runners up 43% of the time

  • 3rd or 4th wins 41% of the time, and finishes runners up 39% of the time

  • 5th or 6th wins 10% of the time, and finishes runners up 11% of the time

  • 7th or 8th wins 6% of the time, and finishes runners up 7% of the time

Those percentages are broadly unchanged from last week, though with another slight increase in the chances of ultimate success for the teams finishing in the top half of the Final 8.

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 a Preliminary Final: Brisbane Lions, Geelong, West Coast, and Richmond (note though that Brisbane Lions, Geelong, and Richmond are more likely to play in a Grand Final than to go out in a Preliminary Final)

  • Lose a Semi Final: Collingwood

  • Lose an Elimination Final: GWS, Essendon, and Western Bulldogs

  • Miss the Finals: remaining teams

In terms of the Flag, we have fair prices of about $4.65 for Richmond and Geelong, $4.85 for Brisbane Lions, $6.70 for West Coast, $9 for Collingwood, $25 for Western Bulldogs, and $33 for GWS.

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 there are now three, roughly equally-likely tiers in terms of likelihood being the Grand Finalists:

  • Brisbane Lions v Richmond: estimated 12.3% chance

  • Brisbane Lions v West Coast or Geelong, and Richmond v Geelong: all estimated 10.1% to 10.5% chances

  • Geelong v West Coast: estimated 9.1% chance

No other pairing has an estimated probability above about 7%.

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