We lost Geelong and the Roos in Week 1 of the Finals and MARS re-rated the six remaining teams, which leaves us (using the same model that we used for Week 1 of the Finals) with the following team-versus-team probability matrix.
Broadly, Hawthorn is expected to beat everyone else fairly handily, except Sydney, which they're expected to beat less convincingly but still beat nonetheless.
Using this probability matrix for 1 million simulations yields the following team-by-team Finals outcome probabilities:
Hawthorn are now estimated to win two-thirds of the time and to make the Grand Final almost 9 times in 10.
Sydney are rated about 4/1 chances for the Flag but are about even money to play in the GF.
The remaining teams are mostly there to mop up the residual probabilities, with none rated better than about 30/1 chances for the Flag and about 5/1 or longer chances to even make the Grand Final. Adelaide, despite finishing 2nd on the ladder in the home-and-away season, are now rated only about 32/1 Flag chances and 15/1 chances of even making the Grand Final.
Simulated Grand Final quinella probabilities appear in this next table. A Hawks v Swans matchup is rated by far the most likely pairing, with a probability approaching 60%.
The next most-likely pairings are Hawks v Pies and Hawks v Eagles, which carry probabilities in the 10-15% range, then Swans v Freo and Swans v Crows matchups, which carry probabilities of around 5%.
Only four other pairings are possible, none of which include the Hawks or the Swans, and none of which are assessed by the simulations as being greater than about 1% prospects.
Amongst these quinellas only the Hawthorn v Sydney pairing at $1.90 offers any value on the TAB AFL Futures market. This wager is assessed as having a 14% edge.
Other TAB AFL Futures market wagers with a positive expectation this week are the Hawks to win the Flag at $1.65 (10% edge), the Hawks to play in the GF at $1.25 (7% edge), and the Swans to play in the GF at $1.55 (8% edge).
Adding these bets to those we've identified in AFL Futures markets in previous weeks yields the following picture:
As you can see, I've closed out those wagers whose fate has already been determined, the net return from which, it turns out, is marginally positive. The ROI from level-staking the identified opportunities is just over 1%.
Having locked in, last week, what look like very promising wagers on the Hawks and Swans at attractive prices on various AFL Futures markets, the current expectation must be for that ROI to grow.
At this point, however, all our eggs are very firmly in two baskets each, appropriately enough, avian based. We'll not know anything more about the fate of these wagers for at least another fortnight.
The first task for this week was to create a model to estimate the probability that one finalist should beat another using only the knowledge of which team was at home and the competing teams' MARS Ratings. Fitting a binary logistic to historical data produced the following model:
Prob(Home Team Wins) = logistic(0.446518 + 0.034125 * Home Team MARS Rating - 0.034161 * Away Team MARS Rating)
Applying that model to the most recent team MARS Ratings yields the following team-versus-team probability matrix:
(Note that, using the fitted model, the probability that Team A defeats Team B when Team A is at home is not the complement of the probability that Team B defeats Team A when Team B is at home.)
Based on the early head-to-head prices for the weekend's Finals, it would seem that MARS rates the chances of the Hawks, Swans and Roos more highly, or rates the chances of the Crows, Pies and Eagles less highly (or both) than does the TAB Bookmaker. It also appears to rate the Cats' and Freo's chances about the same as does the TAB Bookmaker.
Using this probability matrix to simulate the 2012 Finals series 1,000,000 times yields the following team-by-team probabilities:
Hawthorn then are clear Flag favourites, with Sydney on the 2nd line followed by the Pies, Cats and Crows. The Eagles, Freo and the Roos are all rated as rank outsiders to collect the Flag.
Comparing the probabilities in this table with the prices on offer at TAB Sportsbet suggests that the only wagers currently offering a positive expectation are for Hawthorn to win the Flag (28% edge) or to make the GF (11% edge), and for Sydney to win the Flag (5% edge) or to make the GF (24% edge). No other wagers on the Flag or Make the GF markets are worthwhile.
Turning next to potential GF pairings, the simulations yield the following.
Based on these simulated results the only TAB GF Quinella prices offering value are Hawthorn v Sydney at $5.50 (54% edge), Sydney v Geelong at $26 (40% edge), Hawthorn v Kangaroos at $67 (26% edge) and Geelong v Kangaroos at $501 (58% edge). No other pairing has a positive expectation.
The top half dozen most common simulated GF pairings combined represent around 80% of total probability, which means that the remaining 20 potential pairings amongst them account for only 20% of total probability.
(Note that there are only 26 possible GF pairings not 28, because two possible pairings, those reflecting the Elimination Finals, cannot occur in the GF.)
As an interesting exercise, this week I decided to investigate the importance of teams' final ladder positions on their Finals aspirations. To do this I imagined that the teams in the top 8 had finished in a randomised order but with the same MARS' Ratings and hence probabilities of victory against any specified opponent.
I then simulated 1,000,000 Finals series, randomising the order for the top 8 teams for each simulation, and determined that, with randomised team order but with preserved team Ratings, the Flag probabilities would become Hawthorn 39% (down from 57%), Adelaide 6% (no change), Sydney 18% (no change), Collingwood 8% (no change), West Coast 8% (up from 2%), Geelong 13% (up from 8%), Fremantle 3% (up from 1%), and the Kangaroos 4% (up from 1%). Randomisation, it seems. serves mainly to redistribute probability from Hawthorn to the teams that finished in ladder positions 5 through 8.
The summary of this exercise if that, no matter where the Hawks had finished in the eight, on the basis of their MARS Rating superiority they'd still have been Flag favourites. Similarly, the Swans would have been 2nd-favourites regardless of their ladder finish, with Geelong, Collingwood, West Coast and Adelaide all forming the next tier of the market, Geelong foremost amongst them because of its superior MARS Rating. Not even randomisation of ladder finishes could substantially elevate the Flag potential of Fremantle and the Roos however.
Compared to the simulations at the end of Round 20, the latest simulations see:
To help you assess the validity of these latest simulations for yourself, here are the simulated probabilities for the results of each of the remaining 18 games in the home-and-away season, upon which the simulated ladder positions discussed above are based.
Turning to the TAB AFL Futures Markets and using the results of these latest simulations, only two wagers offer an edge of at least 5%:
- Hawthorn for the minor premiership at $2.20 (estimated 7% edge)
- The Roos for a Top 4 finish at $34 (estimated 29% edge)
Here are the results of the new simulations, run using the updated competition ladder and the new MARS Ratings.
(The new results are in grey on the left, while those from last week are provided for comparative purposes and appear in green on the right.)
On a team-by-team basis the major changes are:
Marrying these new simulation results to the current TAB AFL Futures Markets we find value in:
The value we spotted last week in the prices for Geelong to make the 8, Collingwood and Geelong to make the Top 4, and in GWS to win the Spoon has now disappeared, leaving a wager on St Kilda to miss the 8 as the only identified "value bet" that still carries that label.
Here, based on the new MARS Ratings are the updated team-versus-team probabilities that I'll be using in this week's simulations:
Collingwood are still predicted to defeat all-comers, though the likelihood that they'll defeat the Cats has reduced somewhat now that the Ratings Point gap between these two teams has been cut to 7.
Carlton's chances of defeating every other remaining team have risen this week, since it grabbed more Ratings Points than any other during Week 1 of the Finals. Sydney fared next best and so has seen its prospects improve when playing any other team but the Blues. Hawthorn and West Coast, both of which dropped Ratings Points this week, have seen their chances generally decline against the other remaining finalists, although the Hawks still remain favourites over the Eagles, Blues and Swans.
The results of the new simulations appear below, again with the newest data on the left and the outputs from last week's simulations on the right.
Based on these simulations, the Pies chances of winning the flag have barely moved as a result of their win this week and remain at just over 50%. Geelong, however, boosted its chances by just over 5% points, the same amount by which it caused the Hawks' chances to fall.
Carlton's and Sydney's chances rose by just a little, while the Eagle's chances, already slim, all but vanished on Saturday according to the simulation results.
(One additional, interesting element of the simulations is that while the Pies' Flag chances are virtually unchanged, they are now rated more likely to make the Grand Final (up from about 74% to 82%) but more likely to lose it if they do (up from about 30% to 36%)).
Based on these simulated team Premiership probabilities, only the Cats offer any value on the TAB and, at $2.75, it's very little value at that.
In the lower portion of the simulation results I've provided the simulation-based probabilities for each of the remaining possible GF matchups. A Collingwood v Geelong Granny has now firmed to be about a 2/1 on prospect, while the matchups of Geelong v Hawthorn and Collingwood v Carlton Grand Finals are both rated about 7/1 shots and on the second line of betting.
At present the GF quinella market is suspended on the TAB, so I can't say which if any of these pairings offer value.
MAFL is a website for ...
Click on the envelope
Copyright © 2006-2023, Tony Corke. All rights reserved.
