The empirical world is almost always more complex than the theoretical one, which makes life more interesting but statistical modelling more difficult. As I've noted before, swings and roundabouts ...

A simple question: how bad can a team have been in the previous season and still harbour realistic hopes of playing in the current season's Grand Final?

As the 2016 AFL season proper looms and the window for more leisurely analyses slowly closes, today we'll wander across the expanse of footy history this time using MoSSBODS Team Ratings to decide which of the 1,442 teams that have played VFL/AFL football have been the big improvers, and which the big decliners (well ... you find an antonym then).

In the previous blog here on the Statistical Analyses journal, I concluded that Scoring Shots provided, on average, more information about the relative strengths of competing teams than did final scores.

In the previous post here on the Statistical Analyses blog we revisited the topic of Scoring Shot conversion and found that it appears to be unpredictable at a team level across entire seasons. That result, coupled with an earlier one where we found conversion rates to be unpredictable for a given team in a given game (and with some conversations I've had on Twitter subsequent to the more-recent analysis) makes it hard to reject the null hypothesis that team conversion rates are generated in a manner that's indistinguishable from a random variable.

The topic of team conversion rates - the proportion of Scoring Shots that teams convert into goals - and their predictability has come up before here on MoS. 

There's really no answer to the question "Which was the best VFL/AFL team of period X?", but team rating systems like MARS and MoSSBODS provide at least evidence-based panels of candidate teams to argue about.