Within the ChiPS Rating System, winning teams more often fail to accumulate Ratings Points (RPs) than they do within the MARS System. This week, Port Adelaide, Essendon and Geelong all suffered from this characteristic of ChiPS', each winning by a margin smaller than was required of them, Port Adelaide most of all, losing 1.5 RPs despite defeating the Giants by only 35 points.
So difficult, in fact, is it for a team to continually increase its ChiPS Ratings that no team has managed to perform the feat for more than four consecutive rounds, and even that's been done only once, by the Pies from Rounds 2 to 5. Two teams are currently poised to match that record, Sydney and the Gold Coast, each having upped their Rating over the previous three rounds, as you can see in the following table.
The relevant week-by-week and team-by-team data appears at the left of the table, starting with the column headed Delta R1. In that block of numbers you can see the Swans' and the Suns' current streaks, and also glean just how hard it is to put streaks of Rating increases together. Among the eight highest-ranked teams only two of them have grown their Ratings over both of the most recent two rounds.
Streaks of declining Ratings have been a little easier to produce. Carlton managed to shed RPs over the opening four rounds of the season before the Lions went one better by chaining together Points giveaways over the first five rounds of the season. GWS are currently in the midst - or, I guess they'd hope, the end - of a four round losing streak from Round 3 to Round 6, and the Eagles are on the verge of establishing a season record having produced an unbroken string of five declines starting in Round 3.
Despite that - partly because the declines have been relatively small over the past three rounds but mostly because they accumulated almost 13 RPs in the two rounds before the current streak began - the Eagles have climbed four places on ChiPS since the start of the season, the equal-second highest climb of any team. The Gold Coast have also climbed four places while Port Adelaide have climbed seven.
The big fallers have been the Roos, Blues and Lions, all down four places, and the Tigers, down three.
MARS, broadly, agrees with ChiPS, though the team reshufflings have been generally less dramatic. Only two teams have climbed multiple spots on MARS since the start of the season: Port Adelaide up 7 places and the Gold Coast up 4. Four teams have fallen by 2 or more places: the Blues, down 4; the Lions, down 3; and Sydney and the Roos, both down 2.
The correlation between ChiPS and MARS Ratings currently stands at +0.982 and only one team, Fremantle, is ranked more than a single place differently under the two Systems. The broad similarities between the two Systems remains apparent in their respective Ratings charts for each team.
Comparing ChiPS and MARS Rankings with the competition ladder throws up the following teams as having ladder positions most different from their Rankings on one or both Systems:
- Gold Coast, 5th on the ladder but 12th on ChiPS and MARS
- Fremantle, 6th on the ladder but 3rd on MARS (and 5th on ChiPS)
- St Kilda, 12th on the ladder but 15th on ChiPS (and 14th on MARS)
- Richmond, 13th on the ladder but 8th on ChiPS and MARS
- GWS, 14th on the ladder but 18th on ChiPS and MARS
- Carlton, 16th on the ladder but 13th on ChiPS and MARS
Introducing next the Massey, Colley and ODM Systems reveals continuing high levels of agreement with these Systems' team-by-team opinions as well. Whilst some spread remains in the range of opinions about the appropriate ranking of most teams, only for the Gold Coast, where Colley stands alone in its lofty assessment of the Suns, is the range of any real significance.
ODM, as always, provides us with a deconstruction of its opinion into a set of Defensive and Offensive Rankings. Essendon's inability to put points on the Dogs led ODM to significantly drop the Dons' Offensive Ranking this week, while Gold Coast's ton-plus score against the Roos had the opposite effect on its Offensive Ranking. As well, Hawthorn's Defensive Ranking climbed after keeping the Saints to just 30 points, and the Roos' fell as a direct consequence of the same phenomenon that produced the Sun's Offensive Ranking climb.
Adelaide, Carlton, GWS, Melbourne and West Coast are the teams currently with the greatest disparity between their ODM Offensive and Defensive Rankings.
ChiPS still has the best predictive accuracy based on selecting, for each System, the higher ranked team under that System in every contest, regardless of venue.
ChiPS leads MARS by two tips while Massey trails by six, and ODM and Colley trail by 10. Both of the component rankings of ODM have performed better as predictors than has the ranking produced by combining them in ODM itself. Using only ODM Defensive Rankings has resulted in five fewer correct predictions than MARS, while using only ODM Offensive Rankings has resulted in six fewer correct predictions.