2017 - Team Ratings After Round 6

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MoSSBODS now rates Port Adelaide a fractionally better side than GWS after a weekend in which the Giants conceded 28 scoring shots to the Dogs, and Port racked up 40 against the Lions. MoSHBODS also rates the two teams almost equally but puts the Giants narrowly ahead.

Further down the order, St Kilda made significant gains on both Systems, rising four places to 5th on MoSSBODS, and two places to 6th on MoSHBODS. Geelong, Richmond and Hawthorn were the big decliners, slipping between two and four places on both Systems.

The two Systems now agree about the composition of the top 9 teams, and also agree that they're the only ones that are above-average. No team is currently ranked by one System more than two places differently than by the other System.

At the rating component level, both Systems now also agree that the top 3 teams offensively, in order, are Adelaide, Port Adelaide, and GWS. These three teams plus the Western Bulldogs also comprise both Systems' top 4 defensive teams, though MoSSBODS rates Adelaide 1st while MoSHBODS has the Dogs at the top.

The big movers this week were:

  • Hawthorn on offence (down 5 places on MoSSBODS, 4 places on MoSHBODS)
  • Collingwood on offence (up 4 places on MoSHBODS) and on defence (up 2 places on MoSSBODS, 3 places on MoSHBODS)
  • St Kilda on defence (up 6 places on MoSSBODS, 3 places on MoSHBODS)
  • West Coast on defence (up 3 places on MoSSBODS and MoSHBODS)
  • Geelong on defence (down 6 places on MoSSBODS, 7 places on MoSHBODS)
  • Sydney on defence (down 2 places on MoSSBODS, 3 places on MoSHBODS)

Adelaide has now established quite a gap over the second-ranked team on both MoSSBODS and MoSHBODS. We can put the Crows' MoSSBODS rating in some historical context by comparing its current rating to those of every other V/AFL team in history after Round 6 of their respective seasons.

The Crows' current rating is, simply put, very impressive; few subsequent Premiers had a rating as high as Adelaide's at this point in their season. (That Hawthorn 1977 side in the Crows' vicinity is an interesting one. The Hawks had a scoring shot banquet in Round 6 of that year, defeating St Kilda 25.41 (191) to 16.7 (103) to go 4 and 2 for the season. Finishing as runners up in the home and away season, they subsequently went out to North Melbourne in the Preliminary Final.)

We can track Adelaide's ascendancy, as well as the week-by-week rating movements of the other teams, via the animation below.

ChiPS and MARS

ChiPS, like MoSHBODS, has the top 3 teams as Adelaide, GWS and then Port Adelaide, while MARS has gone with Adelaide, GWS and then Geelong.

Geelong also remains ranked quite highly on ChiPS (4th) and provides an interesting exemplar of the different speeds at which the Team Rating Systems on MoS adapt to the most recent results. MoSSBODS, in comparison, now has the Cats ranked only 7th.

Other examples of teams with divergent rankings are:

  • St Kilda, ranked 11th by ChiPS, 8th by MARS, but Top 6 by MoSSBODS and MoSHBODS
  • West Coast, ranked 5th by MARS, but 8th by all three other Systems
  • Richmond, ranked 6th by ChiPS, 11th by MARS, but 9th by MoSSBODS and MoSHBODS
  • Sydney, ranked 7th by MARS, but 10th or 11th by the three other Systems
  • Hawthorn, ranked 13th by MARS, but 16th or 17th by the three other Systems

The extent to which an ELO-style rating system reacts to new information is, as I've said before, a defining characteristic of that system. Systems that react a great deal provide better indications of teams' form, while those that react less provide better indications of underlying team class. Neither characteristic is inherently better than its opposite - it depends on the purpose for which the ratings are being created.

That seems as though it might be an interesting topic for a future blog post, so, for today, I'll leave it there.