2015 - Team Ratings After Round 9

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For all the weekend and mid-week drama on and off the field, the results we ended up with weren't all that far from those the ChiPS and MARS Rating Systems expected.

For ChiPS, the most surprising margins were Port Adelaide's over Melbourne, and the Western Bulldogs' over GWS, both results transferring 2.3 Rating Points (RPs) from the losers to the winners. No other game saw more than 1.8 RPs change hands and the week's average transfer was just 1.4 RPs, the lowest for any round this season.

MARS agreed that the Port and Dogs wins deserved the highest levels of team re-Ratings, but felt that the Eagles win over the Cats was almost equally worthy. Accordingly, it transferred about 4 RPs from loser to winner based on these games' margins. Its average RP transfer was 2.4 points per game, which is low but only the 3rd-lowest for a round this season.

ChiPS' Rating adjustments led to five teams altering Rank this week, all of them now Ranked in the 5th to 9th section of the ladder. The Pies had the most dramatic rise, up three places into 6th, though the Tigers two-spot climb into 5th was also significant. The Roos were the team to fall furthest, sliding three places into 8th. The only other teams to fall, both by a single place, were the Dons and Port Adelaide, but they were very nearly joined by the Hawks who remain the top-Ranked team on ChiPS but lead the Eagles now by just 0.072 RPs. Just a 2-point change in the margin of either of their contests would have been enough to switch their ordering.

MARS, having found the round's results slightly more startling, re-Ranked 11 teams, most notably the Kangaroos, which it dropped four places, Carlton and the Lions, which it dropped two, and Richmond and Collingwood, which it promoted by two spots.

At the end of it all, five teams are Ranked three places or more differently by ChiPS and MARS:

  • Richmond, Ranked 5th on ChiPS and 8th on MARS
  • Essendon (7th and 10th)
  • The Kangaroos (8th and 11th)
  • Adelaide (10th and 5th)
  • Gold Coast (17th and 14th)

The correlation between the two Systems' Ratings now stands at +0.975.

MASSEY, COLLEY AND ODM

The Massey System changed its Ranking of only two teams by more than a single place this week, dropping GWS from 5th to 7th, and promoting Richmond from 13th to 11th. The ODM System, similarly, moved only two teams by this amount or more, dropping Geelong from 9th to 11th, and promoting Richmond from 13th to 10th. That leaves Massey and ODM still with the highest correlation between team Rankings of any pair of Systems. That correlation is now +0.991 and the maximum difference in the two System's Rankings for any single team is just two places, which is what it is for the Dons, Ranked 10th by Massey and 12th by ODM.

Colley was in much more of a re-evaluative mood and shifted seven team's Rankings by a couple of spots or more this week. It promoted Collingwood from 11th to 8th,  Port Adelaide from 12th to 9th, and Richmond from 14th to 10th, while demoting GWS from 3rd to 5th, the Kangaroos from 8th to 12th, Geelong from 9th to 11th, and Essendon from 10th to 13th. The lowest correlation between any pair of Systems' team Rankings is now +0.71 and belongs to Colley and ChiPS. 

Colley is, however, the System whose team Rankings are most highly correlated with the competition ladder. That correlation is +0.930, a fraction higher than the correlation between ODM team Rankings and the ladder (+0.926) and between Massey team Rankings and the ladder (+0.922).

ChiPS' (+0.828) and MARS' (+0.839) correlations with the competition ladder ordering are slightly lower because they Rank a number of teams quite differently from their ladder position, most notably:

  • Adelaide, Ranked 10th by ChiPS but who sit 7th on the ladder
  • Essendon, ChiPS 7th / ladder 10th
  • Geelong, MARS 9th / ladder 12th
  • Gold Coast, MARS 14th / ladder 17th
  • GWS, ChiPS 12th; MARS 13th / ladder 5th
  • Hawthorn, ChiPS 1st; MARS 1st / ladder 6th
  • The Kangaroos, ChiPS 8th / ladder 13th
  • Port Adelaide, MARS 7th / ladder 11th
  • Richmond, ChiPS 5th / ladder 8th
  • The Western Bulldogs, ChiPS 13th; MARS 12th / ladder 9th

ODM Offensive and Defensive Components

ODM changed little about its opinions of the Top 5 Defensive teams this week, which are now:

  1. Fremantle (no change)
  2. Sydney (no change)
  3. West Coast (no change)
  4. Hawthorn (no change)
  5. Essendon (up from 6th)

Essendon took GWS' place in the Top 5, the Giants' lacklustre performance against the Dogs on Saturday sufficient to see it relegated to the 8th-best defensive team according to ODM. 

There was a little more movement amongst the Top 5 Offensive teams this week although this movement was only a reshuffling of the same five teams:

  1. Hawthorn (no change)
  2. West Coast (up 1 place)
  3. Fremantle (down 1 place)
  4. Western Bulldogs (up 1 place)
  5. GWS (down 1 place)

Four teams are now Ranked five places or more differently for their defensive and offensive abilities:

  • Essendon: 5th for Defence, 14th for Offence
  • The Kangaroos: 14th for Defence, 8th for Offence
  • Richmond: 6th for Defence, 13th for Offence
  • The Western Bulldogs: 11th for Defence, 4th for Offence

PREDICTIVE ACCURACY

ChiPS this week drew level with MARS on the simple predictive accuracy metric, Rating the winning team higher than the losing team in one additional contest.

Colley fell one tip further behind and now trails MARS by 12 tips, while the other Rating Systems all matched MARS this week, preserving the gap they carried into the round.