2018 - Round 23 : Overs/Unders Update

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There's quite a range of expected totals across the last nine games of the home and away season. For the MoS twins they cover 154 to 183 points - about a 5 goal range - and for the bookmakers they cover 137.5 to 180.5, which is a 7 goal range.

The 137.5 total is Centrebet's estimate for the Sydney v Hawthorn game, its lowest since the 140.5 it estimated for the same contest back in Round 8 for a game that ultimately produced 150 points. The TAB isn't expecting much more from this game and has set a total of 140.5 for it. Those low figures have dragged the bookmakers' average expected total down to 170 to 171 points per game for the round, a figure that's still a couple of points higher than the MoS twins' averages.

There total agreement this week about which will most-likely be the high- and low-scoring teams, and only moderate levels of agreement about which will most-likely be the high- and low-scoring games.

(Note that I'm still using "Centrebet" to refer to what are now BetEasy forecasts.)

MOST LIKELY HIGH-SCORING GAME

  • MoSSBODS & MoSHBODS: Melbourne v GWS (183)
  • TAB & Centrebet: St Kilda v North Melbourne (179.5 to 180.5)

MOST LIKELY LOW-SCORING GAME

  • MoSSBODS: Richmond v Western Bulldogs, and Sydney v Hawthorn (156)
  • MoSSBODS, TAB & Centrebet: Sydney v Hawthorn (137.5 to 154)

MOST LIKELY HIGH-SCORING TEAM

  • All: Geelong (118 to 126.5)

MOST LIKELY LOW-SCORING TEAM

  • All: Gold Coast (41 to 55)

MoSHBODS' performance was again very good for predicting the high- and low-scoring teams and games last weekend (relative to a naive forecaster), with the high- and low-scoring teams and games all being within its top 3 selections and all assigned a probability greater than that which a naive forecaster would have attached. Specifically, it attached:

  • 15.2% probability to the highest-scoring team, Geelong (against a naive forecast of 5.6% since 18 teams were playing)
  • 19.2% probability to the lowest-scoring team, Fremantle (against a naive forecast of 5.6%)
  • 13.7% probability to the highest-scoring game, West Coast v Melbourne (against a naive forecast of 11.1% since 9 games were played)
  • 13.2% probability to the lowest-scoring game, Carlton v Western Bulldogs (against a naive forecast of 11.1% since 9 games were played)

Those results mean that MoSHBODS now has a season-long performance that is better than a naive forecasters in all four of these markets except low-scoring game.

This week, MoSHBODS has

  • six teams as more likely than 1 in 18 to be the highest-scoring: Geelong, Collingwood, Adelaide, Richmond, Melbourne, and West Coast.
  • four teams as more likely than 1 in 18 to be the lowest-scoring: Gold Coast, Western Bulldogs, Fremantle, and Carlton.
  • five games as more likely than 1 in 9 to be the highest-scoring: Dees v Giants, Saints v Roos, Lions v Eagles, Blues v Crows, and Dockers v Pies.
  • three games as more likely than 1 in 9 to be the lowest-scoring: Swans v Hawks, Tigers v Dogs, and Power v Dons.

WAGERS

Investors have four wagers again this week comprising two unders and two overs bets on estimated overlays ranging from about 2 to 3 goals. 

The relevant weather forecasts are as follows:

  • Port Adelaide v Essendon (Friday, Adelaide Oval - unders bet): Cloud clearing. 0% chance of rain.
  • Richmond v Western Bulldogs (Saturday, MCG - unders bet): Mostly sunny. 0% chance of rain.
  • Sydney v Hawthorn (Saturday, SCG - overs bet): Shower or two. 60% chance of rain. 2-10mm.
  • Brisbane Lions v West Coast (Sunday, Gabba - overs bet): Showers easing. 40% chance of rain in the afternoon. Chance of a thunderstorm. 4-15mm.

Possible rain then for both of the games with overs bets, so those estimated overlays could be optimistic, and no rain at all forecast for the games with unders bets, so no likely assistance from that source.

PERFORMANCE TO DATE

MoSSBODS finished on the right side of TAB and Centrebet totals in five games last week, while MoSHBODS managed six against both bookmakers.

That left MoSSBODS' with a season-long 50% record against the TAB and a 49% record against Centrebet, and left MoSHBODS with a 48% record against the TAB and a 49% record against Centrebet. 

In games where it wagered, MoSSBODS landed 1 from 1 overs bets with the TAB, as well as 1 from 2 overs bets, and 1 from 1 unders bets with Centrebet. That lifted its overall strike rate on overs bets across the season to 37% and on unders bets to 57%.

On the mean absolute error (MAE) metric, MoSHBODS registered the lowest MAEs this week on away team scores and game totals, while the TAB and Centrebet tied on game margins and home team scores.

That left Centrebet still leading on the season-long view for home team scores (MAE of 17.6), game margins (26.1), and game totals (22.5). The TAB still leads on away team scores (17.2).