2015 - Team Ratings After Round 8

/

Again this week there's no movement amongst the Top 4 teams as Rated by ChiPS and MARS, though both Systems remain stubbornly different in their orderings of three of those teams, Hawthorn the exception. ChiPS prefers the Eagles in 2nd ahead of the Dockers and then the Swans, while MARS thinks the Dockers are 2nd best, the Swans 3rd, and the Eagles 4th. 

The maximum disagreement between the two Systems in the Ranking of any of these Top 4 teams is just two places with larger disagreements only evident for teams further down the ordering. Differences of at least four places exists for:

  • Adelaide, which ChiPS Ranks 9th and MARS 5th
  • Essendon (6th and 10th)
  • Geelong (11th and 7th)
  • Richmond (5th and 9th)

On ChiPS, only three teams have accumulated Rating Points (RPs) for the three most recent rounds, these being Sydney, GWS and West Coast, the latter actually having an accumulating RP run extending to five straight weeks. 

Similarly, only three teams have decumulated RPs for three or more weeks in a row: Port Adelaide, Carlton and the Gold Coast.

The correlation between ChiPS and MARS Ratings now stands at +0.974, which is the highest correlation they've displayed all season. (That said, the correlation has never dropped below +0.955, so it's not as if they've ever been significantly divergent.)

COLLEY, MASSEY AND ODM

Time then to bring in MoS' other Team Rating Systems where we find that Colley continues to display the most divergent opinions of all the Systems, especially for:

  • Collingwood, which it Ranks 11th and no other System Ranks lower than 8th (and who sit 5th on the competition ladder)
  • GWS, which it Ranks 3rd and no other System Ranks higher than 5th (and who sit 4th on the competition ladder)
  • Hawthorn, which it Ranks 7th and no other System Ranks lower than 2nd (though they sit 7th on the competition ladder)

Looking at pairwise comparisons, Colley's team Rankings are most divergent from ChiPS', the rank correlation between them now standing at just +0.66. The correlation between Colley's and MARS' Rankings is only a little higher at +0.71. At the other end of the scale, Massey's and ODM's team Rankings are now almost identical, their sole disagreement relating to the proper ordering of Essendon and Geelong, and the correlation between their Rankings standing at a massive +0.99.

Three teams are notable in that their Rankings by the two ELO-style Rating Systems, ChiPS and MARS, are quite different from their Rankings by the three other Systems:

  • GWS, which ChiPS and MARS Rank lower than Colley, Massey and ODM
  • Richmond, which ChiPS and, to a lesser extent MARS Rank higher
  • The Western Bulldogs, which ChiPS and MARS Rank lower

For the Giants and for the Dogs, much of the discrepancy in their Rankings by ChiPS and MARS in comparison to the other Systems stems from the relatively low Ratings they both brought into the season. Colley, Massey and ODM bring no such pre-conceptions with them into a season, and the extent to which this is a good or a bad thing will only be assessable once the season progresses further.

For the Tigers, the story's different. Their higher Ranking by ChiPS and MARS has nothing to do with the Ratings they carried across into the season and everything to do with how each of their performances is weighted and used to create a current Rating. Simply put, MARS and ChiPS have been relatively more impressed with the Tigers' results in 2015 than have Colley, Massey and ODM.

ODM Offensive and Defensive Rankings

The ODM System now has three teams with Defensive Rankings more than three places lower than their Offensive Rankings, and two teams for which the opposite is true:

  • Adelaide are Ranked 12th Defensively and 6th Offensively
  • Geelong (13th and 8th)
  • The Kangaroos (14th and 9th)
  • Essendon (6th and 14th)
  • Sydney (2nd and 7th)

The largest down-Rankings in recent weeks by ODM have been for Adelaide's defence, Gold Coast's offence, and for Port Adelaide's defence and offence, while the largest up-Rankings have been for Geelong's offence, GWS' offence, and Richmond's defence.

Simple Predictive Accuracy

MARS gave up ground to every other System this week excepting the Offensive Component of ODM, which predicted the same number of results as did MARS (using the simple heuristic of selecting the team with the higher pre-game Rating).

MARS dropped one tip to:

  • ChiPS, which now trails MARS by only a single tip 
  • Massey and ODM, which both now trail MARS by six tips
  • Colley, which now trails MARS by 11 tips.

The Defensive Component of ODM performed even better relative to MARS, tipping two more results correctly to close the gap between it and MARS to eight tips. The Offensive Component of ODM, tying this week with MARS as it did, remains seven tips behind.