I introduced the Massey and Colley Ratings Systems to MAFL in the second half of season 2011. This week we'll take a look at these Systems for the first time in 2012 and compare their opinions with those of MAFL's own MARS Ratings.
For the first time I can remember after a home-and-away round, the ranking of all teams based on MARS Ratings is unchanged from the previous round. That's not to say that there were no changes in the Ratings themselves, just that they were small enough and specific enough to leave the MARS Ladder as it was at the end of Round 3.
The teams with MARS Rankings much higher than their positions on the Competition Ladder continue to be Collingwood (7 places higher), their fellow Grand Finalists, Geelong (also 7 places higher), and Hawthorn (also 7 places higher). Conversely, the teams with MARS Rankings much lower than their Ladder positions are Sydney (5 places lower), Essendon (6 places lower) and Adelaide (also 6 places lower).
Essendon, Fremantle, Sydney, Hawthorn and St Kilda have also accumulated RPs, each adding about 6 or 7 RPs across the season so far. Adelaide, Richmond, the Roos and the Lions are the only other teams to have accumulated RPs.
The largest RP losers have been the Dogs, the Suns and the Dees, each of which has given up at least 9 RPs. Geelong, GWS and Collingwood are the only other teams to have surrendered a significant number of RPs across the 4 rounds to date.
All told, 11 teams have been net accumulators of RPs and 7 have been net losers so far, and the combined RPs surrendered by the three most profligate donors are matched only by the 5 most acquisitive.
At this point in the season, as teams' carryover Ratings continue to have a large effect on their MARS Ratings, it's not particularly remarkable (though remark I will) that the Colley and Massey Ratings and Rankings are more similar to one another than they are to those of MARS.
Specifically, the rank correlation between Massey and Colley Ratings currently sits at +0.85 and the correlation between the team Rankings based on these Ratings is also at +0.85.
In comparison, the correlation between MARS and Colley Ratings is +0.58, between MARS and Colley Rankings is +0.67, between MARS and Massey Ratings is +0.79, and between MARS and Massey Rankings is +0.82. These correlations are all still positive and high, however, so it's not as if they all appear to have been watching different games.
The teams responsible for much of the disparity between MARS and the other two Systems are:
- Collingwood (ranked 5th by MARS, yet 10th by Colley and Massey)
- Geelong (ranked 3rd by MARS, but 9th by Colley and Massey)
- Hawthorn (ranked 2nd by MARS, but 8th and 4th by Colley and Massey, respectively)
- Sydney (ranked 7th by MARS, yet 1st and 2nd by Colley and Massey, respectively)
For many other of the teams, only one of Massey or Colley agrees with MARS but they disagree with one another: for example, Adelaide are ranked 13th by Massey, 11th by MARS, but 7th by Colley; Essendon are ranked 6th by Massey, 9th by MARS, yet 2nd by Colley; St Kilda are ranked 8th by Massey, 6th by MARS, but 12th by Colley; and the Roos are ranked 6th by Colley, 8th by MARS, but 3rd by Massey.
That all said, I think it's remarkable that, after only 4 rounds of football, these 3 quite different Rating Systems find so much to agree about.