2015 - Team Ratings After Round 12

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Some unexpected results on the weekend led to larger-than-normal changes in ChiPS Team Ratings, which, in turn, led to four pairs of teams trading places on ChiPS Rankings. The teams rising were the Roos, Dons, Dogs and Blues, they respectively taking the places of the Pies, Crows, Giants, and Saints.

Despite losing, Richmond acquired ChiPS Rating Points (RPs) this week because it performed slightly better than ChiPS expected after adjusting for the sizeable, negative HGA that it uses for Richmond home games at the G. Though I was initially reluctant to impose such an apparently anomalous home ground "penalty" on the Tigers, results so far this season suggest that the adjustment has been appropriate, as evidenced by the table at right, which provides Mean Absolute Errors (MAEs) for C_Marg margin predictions for each team, split on the basis of whether the team was playing at home or away. The MAE for Richmond home games is just 26 points per game, the 5th-best MAE for all teams playing at home.

A quick scan of the table also reveals that the Brisbane Lions, Geelong, Gold Coast, GWS and Kangaroos have regularly performed contrary to ChiPS' expectations, while Adelaide, Carlton, Essendon, Fremantle and Sydney have performed most often in accordance with ChiPS' pre-game assessments.

Where ChiPS re-Ranked eight teams this week, MARS re-Ranked nine, though only three by more than a single place, the Dogs jumping two places into 11th, and the Dees two places into 14th, with the Suns slipping two places into 16th.

That leaves four teams Ranked more than two places differently by ChiPS and MARS:

  • Richmond (Ranked 5th on ChiPS and 8th on MARS)
  • Kangroos (6th and 10th)
  • Essendon (9th and 12th)
  • Adelaide (10th and 6th)

Correlation between ChiPS and MARS Team Ratings remains high (+0.965), as does the correlation between ChiPS and MARS Team Rankings (+0.934).

MASSEY, COLLEY AND ODM

Massey made the fewest team re-Rankings this week but still changed its mind about seven teams, most dramatically on the Cats, which it dropped from 6th to 10th, on the Roos, which it elevated from 12th to 9th, and on Port Adelaide, which it dropped from 8th to 11th.

ODM re-Ranked eight teams, including moving Adelaide from 11th to 8th, Geelong from 7th to 10th, and the Roos from 12th to 9th, while Colley re-Ranked nine teams, among them Geelong (8th to 11th), GWS (5th to 8th), the Roos (11th to 7th), Richmond (6th to 9th), and the Dogs (9th to 6th).

Those moves leave Massey and ODM as the two Systems with the least divergent Team Rankings, the correlation between those Rankings now standing at +0.994 and the difference between the Rankings for no single team exceeding more than one place. ChiPS and Colley have the widest divergence of opinion, the correlation between their Team Rankings now standing at +0.851, a direct reflection of the fact that the two Systems disagree by three places or more about the Rankings of eight different teams.

Only four teams are now Ranked by any System more than three places differently from their Ranking on the competition ladder:

  • Essendon (Ranked 9th by ChiPS; 13th on the Ladder)
  • GWS (Ranked 12th by Massey and ODM, 13th by ChiPS and MARS; 6th on the Ladder)
  • Hawthorn (Ranked 1st by ChiPS, MARS, Massey and ODM; 5th on the Ladder)
  • The Kangaroos (Ranked 6th by ChiPS, 7th by Colley; 11th on the Ladder)

ODM OFFENSIVE AND DEFENSIVE RANKINGS

ODM still includes the same five teams in its Top 5 for Defence, though it has again changed their order:

  1. Fremantle (up from 2nd)
  2. Sydney (up from 3rd)
  3. Hawthorn (down from 1st)
  4. Richmond (up from 5th)
  5. West Coast (down from 4th)

Geelong, somewhat surprisingly given its most recent result, has moved into ODM's Top 5 teams for Offence, that list now comprising:

  1. West Coast (no change)
  2. Hawthorn (no change)
  3. The Kangaroos (no change)
  4. Geelong (up from 6th)
  5. GWS (down from 4th)

Eight teams now have Offensive and Defensive Rankings that differ by six places or more:

  • Essendon (7th on Defence, 16th on Offence)
  • Fremantle (1st and 10th)
  • Geelong (13th and 4th)
  • Gold Coast (12th and 18th)
  • GWS (11th and 5th)
  • Kangaroos (14th and 3rd)
  • Richmond (4th and 13th)
  • Sydney (2nd and 11th)

PREDICTIVE ACCURACY

ChiPS and MARS remain locked in terms of simple predictive accuracy (basing predictions solely on superiority in Team Rating), both now eight tips ahead of the Offensive Component of ODM, nine tips ahead of Massey and ODM, 10 tips ahead of the Defensive Component of ODM, and 15 tips ahead of Colley.