At the heart of any Elo-based system is the parameter k, which determines how responsive the system is to a single result, and it’s always a worry early in the season how well that k has been chosen.

This week, that k has seen the Pies rocket to top spot on both MoS Systems, ahead of the Cats and the Swans in that order on MoSSBODS, and the Swans and the Cats in that order on MoSHBODS.

Overall, 17 teams were re-ranked by MoSSBODS, and 13 by MoSHBODS, 8 by multiple spots on MoSSBODS, and 7 by multiple spots on MoSHBODS. The big movers were:

• Collingwood (up 3 places on MoSSBODS and 4 places on MoSHBODS)

• Port Adelaide (down 3 places on both)

• Western Bulldogs (down 3 places on both)

The correlation between MoSSBODS and MoSHBODS Combined Ratings now stands at +0.9912.

On the Component Ratings, on offence we find both Systems with a Top 3 of Pies, Cats, and Swans, while on defence we find MoSSBODS with a Top 3 of Saints, Pies, and Dees, and MoSHBODS with Saints, Swans, and Dockers.

To put the latest MoSSBODS Ratings in some historical context, here are the Ratings of all teams after Round 2 across V/AFL history.

Only Collingwood, Geelong, and Sydney are in the top 50% of teams that eventually went on to make the Grand Final.

On MoSSBODS, 7 teams are now rated positively on offence and defence (no change), 6 are rated negatively on both (down 1, 2 are rated positively on offence but negatively on defence (up 1), and 3 are rated negatively on offence but positively on defence (no change). The correlation between the teams’ MoSSBODS offensive and defensive Ratings now stands at +0.514, which is quite low by historical standards. Could we perhaps be seeing a slight uncoupling between teams’ offensive and defensive abilities? It’s early days yet, but it’ll be an interesting ting to watch.

And, finally, to MARS, which re-ranked only 10 teams this week, none of them from positions 13 through 18.

There was considerable movement at the top, however, with Sydney rising two spots into 1st, shuffling Geelong into 2nd, and Melbourne into 3rd.

Further down we had Port Adelaide, Fremantle, and Western Bulldogs all dropping two spots, and St Kilda rising three.

Just 10 teams are now rated as better-than by MARS, although we have Essendon on 999 and the Western Bulldogs on 997, which is fractionally below average.

The Rating gap between first and last currently stands at just over 49 Rating Points, which is down by about 2 Rating Points on where it was last week. The gap between first and eighth now stands at just over 16 Rating Points, which is down about 2 Rating Points compared to last week.

Looking across the rankings of all three Systems and ordering the teams based on the current competition ladder, we find relatively large differences for a number of teams in terms of their rating-based rankings.

(There are, still, even greater differences relative to the teams’ ladder positions, especially for St Kilda, Essendon, North Melbourne, and West Coast where ladder positions seem “too high”, and for Melbourne, Port Adelaide, Geelong, and Western Bulldogs where ladder positions seem “too low”.)

MARS provides the most outlying rankings of the three Systems, it having the outright most-extreme ranking for 10 of the teams, although this week it is joined by MoSSBODS on that number. MARS is especially different in terms of its Collingwood ranking of 5th - the MoS twins have them 1st.

By comparison, MoSHBODS has the outright most-extreme ranking for only two teams.

Lastly, if we consider the range of rankings that the three Systems have attached to each team, we find that Collingwood (4 spots) has the widest range of rankings, while 14 teams have rankings than differ by no more than 2 spots, including Fremantle and St Kilda, for which all three Systems have the same ranking.