2017 - Round 25 (Week 2 of the Finals) : The Two Sydneys

There's little debate this week amongst the Head-to-Head Tipsters about which teams will progress to the Preliminary Finals, with Consult The Ladder and Home Sweet Home the only dissenters, and they only in the Cats v Swans game.

Consequently, MoSSBODS_Marg's lead remains safe this week, which means that it will enter the Preliminary Finals with a two tip lead and just three games to play. It is also, we should probably remember, eight tips ahead of Bookie Knows Best.

MoSSBODS_Marg has gone out on something more resembling a limb amongst the Margin Predictors, however, where it finds itself Predictor Most Extreme in forecasting the rosiest margins for the home teams in both games.

Bookie_3 is the most pessimistic about the Cats' chances, and ENS_Linear least optimistic about the Giants' chances.

MoSHBODS_Marg now leads RSMP_Simple by about 8 points, and will see that gap change depending on the outcomes of each game roughly as follows:

  • Increase by 3 points if Sydney win by 10 points or fewer and decrease by 3 points if Sydney win by 13 points or more
  • Increase by 3 points if GWS win by 17 points or more and decrease by 3 points if GWS win by 14 points or fewer

Worst case then, MoSHBODS_Marg will still lead by about 2 points at the end of the round. The two RSMP Predictors will continue to fill the 2nd and 3rd places as MoSSBODS_Marg's forecasts are insufficiently different this week for it to close the substantial gap between it and those RSMP Predictors.

For the Head-to-Head Probability Predictors, the broader range of estimates have come in the Geelong v Sydney clash where Bookie_RE's 31% and MoSSBODS_Prob's 44% define a 13% point range. In the other game, the extremes are Bookie_OE's 68% and MoSSBODS_Prob's 77%.

MoSHBODS_Prob, the current leader, will suffer most if Sydney win and GWS lose, though the damage will be minimal in both cases.


With such limited divergence of opinion in the Giants v Eagles game, it's unsurprising that the entirety of the round's head-to-head and line action comes in the Cats v Swans game.

Investors have in that game a modest head-to-head wager at $3 on the Cats, and an even more modest wager at $1.90 on the Cats +16.5.

That said, in the line market for the GWS v West Coast game, were the Giants being asked to give even a single point less start (ie 15.5 points or less), Investors would have had a wager here too.

In total, the two wagers on Geelong represent just 0.7% of the Overall Portfolio, all of which would be lost if Geelong were defeated by 17 points or more.

A win by Geelong would see 1% added to the value of the Overall Portfolio, while a draw would add 0.5%, and a Geelong loss by 16 points or fewer would represent approximately a break-even result.

Moving next to total scores we find that all four forecasters are predicting two low-scoring Semi-Finals.

MoSSBODS and MoSHBODS have the round's low-scoring team as West Coast, high-scoring team as GWS, and the high-scoring game as the Geelong v Sydney clash. The TAB and Centrebet agree that GWS is the likely high-scoring team, but have Geelong as the low-scoring team, and the GWS v West Coast game as the high-scoring clash.

The overlays relative to the two bookmakers for that GWS v West Coast game are very small, however, so Investors have no wager. In the Geelong v Sydney game the overlay relative to Centrebet is, however, just large enough to warrant an overs bet in that game.

Last week, MoSSBODS finished on the right side of the Total with the TAB in 2 of the 4 games, and with Centrebet in 3 of the 4 games, while MoSHBODS finished on the right side of both the TAB and Centrebet in 3 of the 4 games.

As a result, MoSSBODS' and MoSHBODS' season-long records against both the TAB and Centrebet are now identical at 104 from 202 (or 51.5%).

In terms of mean absolute errors (MAEs), last week MoSHBODS outperformed on every metric with an MAE on game Margins of 25.5 points per game, on Home team scores of 23.1 points, on Away team scores of 13.7 points, and on Totals of 24.0 points points per game.

That moved MoSHBODS into the lead with the best season-long performance on game Margin (28.6), left Centrebet still with the best MAE for Home team scores (17.8) and the TAB with the best MAE on Away team scores (17.2) and on Totals (20.7).

It's interesting to note in passing that all four forecasters have found Away team scores easier to predict than Home team scores so far this season. Whether that's historically been the case might be an interesting topic for a future analysis.