Matter of Stats

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2020 - Team Ratings After Round 9

When Ratings are compressed, it doesn’t take much to see teams move multiple places, and this week saw MoSSBODS and MoSHBODS move eight teams by 2 spots or more.

That included their previous Number 1s, Collingwood, who now find themselves in 4th.

Port Adelaide returned to the top on both Systems, now ahead of Richmond and Brisbane Lions.

Despite the reshuffles, only seven teams are ranked differently by the two Systems, and only one, West Coast, by more than a single spot. There also remains a high degree of correlation about the underlying ratings themselves. That correlation now stands at +0.9975.

Ratings remain compressed at the top such that, on MoSSBODS, 1st and 10th are now separated by only 4.8 Scoring Shots, while on MoSHBODS, 1st and 10th are separated by only 17.4 points.

Based on the similarity of Combined Rating, you could form the following rough groups based on the latest results:

Top Tier (span 2 Scoring Shots / 6.3 Points): Collingwood, Brisbane Lions, Port Adelaide, Richmond, and Geelong (no change)

Middle Tier (span 2.3 Scoring Shots / 7.8 Points): St Kilda, Hawthorn, Carlton, West Coast, Western Bulldogs, Melbourne, and GWS (GWS rejoining)

Bottom Tier (span 2.9 Scoring Shots / 11.2 Points): Essendon, North Melbourne, Gold Coast, Fremantle, and Sydney (GWS exiting)

Outliers: Adelaide.

On the Component Ratings, on offence we find MoSSBODS with an unchanged Top 3 of Lions, Power and Tigers, and MoSHBODS now with the same Top 3 after elevating the Tigers from 5th. On defence, MoSSBODS has a Top 3 of Collingwood, Richmond, and now Port Adelaide, and MoSHBODS has a Top 3 of Collingwood, Port Adelaide, and Richmond.

On MoSSBODS, 4 teams are now rated positively on offence and defence (down 1), 5 are rated negatively on both (down 1), none are rated positively on offence but negatively on defence (no change), and 9 are rated negatively on offence but positively on defence (up 2). The correlation between the teams’ MoSSBODS offensive and defensive Ratings now stands at +0.61.

And, finally, to MARS, which continues to hold quite different views about a number of teams, though it also re-ranked a slew of them this week.

It now has a Top 3 of Richmond, Brisbane Lions, and Geelong, and has the MoS twins’ Number 1 team of Port Adelaide only in 4th.

It moved nine teams by more than a single spot this week, including a four-spot promotion for North Melbourne, a three-spot promotion for Brisbane Lions, and a three-spot demotion of Collingwood.

Only eight teams are now rated as better-than-average by MARS, with the gap between the 1st- and 8th-ranked teams only 14.9 Rating Points (probably the equivalent of about 12 to 13 points in a typical season with full-length quarters). The gap between 1st and 5th is now under 5 Rating Points.

Forming rough team groups, as we did for the MoS twins, we might get:

Top Tier (span 8.1 Rating Points): Richmond, Brisbane Lions, Geelong, Port Adelaide, West Coast, and Collingwood

Middle Tier (span 11.8 Rating Points): GWS, St Kilda, Hawthorn, Western Bulldogs, and North Melbourne

Bottom Tier (span 20.1 Rating Points): Essendon, Carlton, Melbourne, Sydney, Fremantle, Gold Coast, and Adelaide

Looking across the rankings of all three Systems and ordering the teams based on the current competition ladder (using competition points per game as the primary basis for that ordering), we still find Essendon and Gold Coast as the teams highest on the ladder ranked lowest by the Systems, and Richmond and Hawthorn as the teams lowest on the ladder ranked highest by the Systems.

MARS continues to provide the most outlying rankings of the three Systems, it having the outright most-extreme ranking for 15 of the teams, with Port Adelaide, Carlton, and GWS the most notable examples.

By comparison, MoSSBODS has the outright most-extreme ranking for six teams, and MoSHBODS for only one team.

Lastly, if we consider the range of rankings that the three Systems have attached to each team, we find that Carlton and GWS (5 spots) have the widest range of rankings, while 12 teams have rankings than differ by no more than 2 spots, including three teams for which all three Systems have the same ranking (Western Bulldogs, Fremantle, and Adelaide).