The Model takes on the World

 

Hi all. This is just a quick post following on from last weekend’s post, in which we detailed a statistically driven model for Brownlow prediction. In case you have missed it, the vote count is tomorrow and we have hope everyone is ready to roll. In our previous post we included one iteration of results from our 2016 prediction, which was run using the Random Forest machine learning method, and we got quite a few questions about how useful it was for betting and what its limitations were. The aim of this blog post is to highlight some of the significant differences between our model and bookies probabilities,  in this case Sportsbet, and perhaps how these differences could be used to find some value. Like last time, this is just our own number crunching and interpretative dribble so if you are going to use it to bet you do so at your own risk! For all you know I am drunk right now as I write this.

One of the key findings from our earlier blog was that the reliability in the model decreased the higher in the rankings you got. As fun as it is to bet on the top 10, and it’s still possible some value could be derived from the model, to use it properly we need to heed our own advice and concentrate on the less interesting lower down results. With that in mind I have chosen several of the “Team Voting” betting markets and also some “Will they poll more than last year?” markets to have a closer look at.

Note: All odds are Sportsbet unless otherwise stated and were correct at the time of writing (Sunday evening when I should be doing almost anything but this).

gwilt

Essendon legend James Gwilt has a small chance of getting a vote in round 4. Get around him.

Hawthorn most votes w/o Lewis and Mitchell.

Both our model, all the bookies, my Nan and the AFL and Phantom prediction sites give almost no chance for any other combination than Mitchell followed by Lewis for most votes at Hawthorn this season. For that reason, Sportsbet has a market without them in it. Cyril is favourite at $1.66 and Isaac Smith has odds of $3.25. Our algorithm predicts Cyril to get 5 votes and Isaac with 8, which obviously offers some potential value. We decided to drill down into the results and see if anything weird was going on. Sorry for the low quality of images, I didn’t have time to teach myself the html required to generate nice ones (the Brownlow is tomorrow after all).  We have coloured relevant rounds with green for agreement, yellow for votes predicted by us and not the AFL or Phantom, and red where the model hasn’t predicted on probable games.

The “Model” row is actually what the algorithm generates – the percentage chance of the player acquiring 3 votes (its important to note – this isn’t relative to other players in the game, its relative the global population and statistical signature of a “3 vote game”. Three players could get 100% in a game, or a player could be most likely to get 3 votes with a 40% modeled likelihood).

AFL HAWTHORN COLLINGWOOD

Cyril ($1.66):cyril2

  • Round 12: Hawthorn beat Essendon by over 100 points, so there are a lot of players to fit in, but Cyrils 20 disposals and 3 goals must have a chance here. He is special after all (Verdict: more likely 1 vote, possible none).
  • Round 20: Cyril was the best Hawk, but in a loss to Melbourne where Viney and Gawn starred it seems unlikely he will get any more than 1 vote. (Verdict: 1 at most)
  • Round 23: AFL predictor has him at 3 votes, noone on earth does. Our model gives him 5% chance of 3 votes, and Phantom gives him no love at all (Verdict: Bruce apparently did the voting for the AFL website – likely no votes).

Isaac ($3.25):isaac2

  • Round 11: This round is key if Smith is going to outvote Cyril as Rioli is in with a chance as well. The model gives him a 62% chance, which is strong but far from definite. Hawthorn beat Melbourne, but general consensus is that Dom Tyson was best on ground. Smith in “with a chance”, after 29 disposals and 108 DT points. (Verdict = Mitchell and Tyson more likely, but Smith a chance for 1 or 2).

Betting summary: According to our model, the chances of Cyril scoring more than 5 votes are slim. It is Cyril though, and he doesn’t need a lot of stats to look “special”. $3.25 seems pretty good odds for Isaac Smith to score 6-8 votes and outscore him.

St Kilda Most Votes:

Jack Steven is essentially a lock to get the most votes for the Saints this year, with a projected 20-21, including 15 guarantees from 5 games. Our model however strips him of a 3 and suggests Nick Riewoldt is a good chance to poll higher than projected. Will it be enough?

1466925122734

Nick’s likely vote count in round 20. 

Jack (1.04):jacksteven

  • Round 14: This round is KEY if Riewoldt is going to have any chance of getting more than Steven. The model is in almost total agreement with Phantom and AFL, with 5 clear best on grounds and a couple of 2 vote games. The big difference is round 14, a big upset by St Kilda to get over Geelong by 3 points. Seb Ross was clear best on ground, according to everyone but the AFL, however who gets the 1 and 2 votes seems a lot more contentious and it could be a raffle between Steven, Henderson and Riewoldt. Steven was relatively statistically quiet by his lofty 2016 standards, getting 25 disposals and a couple of tackles, which accounts for his relative low modeled chance (25%). Riewoldt got his trademark 26 touches, 10 marks but no goals. Verdict: Anyone’s guess, but critical.

Nick ($8.00):riewoldt

  • Round 2: The Saints got smashed by the Bulldogs in this game, but Riewoldt still managed to get 23 disposals, 13 marks and 2 goals. Verdict: If he is to get votes in this game, umpires will need to be giving a charity vote for his 300th, as he wasn’t his normal efficient best.
  • Round 20: Riewoldt had 26 disposals and 16 marks however he was not named in the best in the AFL website, and was only given 51% chance by our model. Verdict:  Seems unlikely , but maybe commentators are just used to 26 and 16 from him?

Betting summary: Riewoldt is 8-1 odds for most votes at Saints, which means Sportsbet has given him 12.5% chance of victory. Our model gives him up to 40% chance of victory, with a significant chance of a tie. For this to happen, round 14 is critical, and he will need to get well clear of the 15 points Stevens is all but guaranteed. Its seems unlikely, but if you are looking for some risk this one will be fun. Can we all give a round of applause for Saint Nick at age 34 as well?

Port Adelaide Most Votes:

Our model gives both Robbie Gray and Ollie Wines 17 votes – startlingly and worryingly different to the AFL, Phantom and the bookies (Sportsbet has Wines at $11). To quote Seth Eisenburg:

“If it looks like shit, smells like shit, and feels like shit, you don’t have to actually eat it to know it’s shit.”

Regardless, we are going to eat it!

Robbie Gray ($1.01)gray

  • Round 2: Our model actually gives Robbie Gray more votes than the other prediction methods, which makes the Wines prediction even more strange and unlikely. The main anomalous round is Port Adelaide’s loss to cross time rival Adelaide. Robbie Gray had 37 disposals and kicked a goal, but the Power went down by 60. Verdict: a chance of a vote, but Lynch, Betts, Jenkins and Laird good in a big win. This drops Gray to a likely 15-16 votes, but significant upside.

Ollie Wines ($11.00)wines

  • Round 11: Ollie Wines is not mentioned in the best in the Powers big win over Collingwood, but he did have 24 disposals, 14 of them contested (hence the 51% chance). Verdict: Maybe a sneaky for 1 vote, but unlikely for many more.
  • Round 15: Travis Boak seems a lock for the 3, although the model has Wines as more likely. Verdict: A likely 2 votes for Wines.

Betting summary: If you take into account the potential increase in Robbie Gray’s score on the AFL and phantom predictions, and the slight decrease in Wines after looking at other predictions, it actually does seem possible both players could score around the 15-16 vote mark. Robbie Gray still has to be the favourite; he has the runs on the board with votes and has less question marks, but at $11 dollars it may be worth a small flutter on the thunderous thighs of Ollie Wines.

ollie-wines-resize

Ollie likes those odds.

More than last year bets:

Tom Mitchell:

Mitchell is $2.50 to beat his total from last year of 12 votes. I didn’t realise until I went through his stats how much of a monster this guy is. If Hawthorn get him and J’OM, I quit.

mitchell

  • Round 16: 33 disposals and 6 tackles – definitely a chance of votes.
  • Round 7: A small chance of 1 vote but unlikely with Heeney and Lance Franklin obtaining 11 goals between them in a domination against Essendon. He did rack up 37 disposals though.
  • Round 20: 39 disposals, 9 marks and 7 tackles still might not be enough in this game.

Bet summary: Tom Mitchell is a statistical beast and the algorithm has rewarded him as such. However, when you dig down into the statistics, it appears that his team mates may damage his chances significantly. Its possible, but the odds aren’t good enough for us. Avoid.

850754-4c0d1ae0-df0f-11e3-9096-801fbb4e8d9b

Probably how he gets so many possessions. 

Scott Pendlebury:

Scott Pendlebury is one of the elite midfielders of the competition and has consistently picked up votes over his illustrious career. With injury and a switch to the HB flank, 2016 wasn’t his finest year and our gut feeling was that he would be unlikely to finish above his 15 votes from last year. Our model strongly agrees, predicting him to get 9, which is significantly different from the AFL and Phantom predictions  of 13 and 14 respectively. Sportsbet also agrees, giving odds of $1.65 for him not to make it. That being said, never turn your back on a champion, and especially don’t turn your back on someone from Collingwood.

pendles

  • Round 9: Round 9 is the issue here, with the model giving him a 56% chance of votes, but not putting him in the top 3. It seems the model may have underestimated Pendlebury’s influence as his 26 disposals and 3 goals seems likely to be enough to get him at least one vote (and the match reports agree).

Bet Summary: Like Cyril, Pendlebury’s statistics sometimes don’t reflect the influence he has a on game. That being said, the model backs up Sportsbet and suggests that the $1.65 on offer for him not to make 15 votes is fairly safe money. Maybe throw it into a funner multi for some extra value.

Dayne Zorko:

It’s fair to say Brisbane had a shit-house year, and as an Essendon supporter I pity yet still loathe them. This guy isn’t to blame though and it seemed sometimes he was the only player who cared. Sportsbet has him at $3 to not get his 2015 total of 5 votes, however, our model suggests he may be hard done by  and there may be some value.

zorko

  • Round 4: AFLPA gave him 2 votes in Brisbane’s win over Gold Coast, although he wasn’t mentioned in the other game ratings. Verdict: Possible for 1, but 2 unlikely.
  • Round 18: Zorko played well in a domination against Essendon, and was listed in the best, but seems unlikely to get the votes over Rockliff, Rich and Martin.

Bet Summary: The model says 6, but it doesn’t seem to be a solid 6. Avoid, or go for the tie (which at $4.50 may actually be a solid bet).

summary

Summary of votes for mentioned players. These results were taken over 100 iterations. 

Running out of time, so that is all for now. Good luck tomorrow, if anyone uses these in their decision making and it works, let us know! If all of these predictions are wildly wrong, I will be deleting this blog so good luck finding us.

Notes:

Sportbet BYO: We came across this late, but Sportsbet offer custom made bets. You simply send them details of your bet and they work it up for you. It’s probably too late, but using a system like this for a model like ours may have some benefit.

3 Votes: J…..Gwilt (Ess)

 

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