## Is it possible to predict how a relegated team will perform in the championship?

There is a pretty simple premise for this post: by looking at the performances of teams the year they are relegated from the premiership can we predict how they will fare the following season in the championship? First the ‘average’ season for these teams, with points and ± on a per game basis

 League PpG ±pG SOTR PDO Premiership (‘Year 1’) 0.81 -0.79 0.411 945 Championship (‘Year 2’) 1.58 +0.31 0.540 1019

So the relegated teams perform better in the championship (as a group their SOTR improves and their PDO regresses to the mean) but that’s no surprise, the quality of competition is appreciably lower in the championship (for example it is much easier to score and prevent goals). Obviously some of the teams that are relegated are better than others so what I really want to know is whether it’s possible to predict how an individual team will perform rather than the population as a whole.

To do this I’ve taken the performance of each team and made a plot of the values in ‘year 1’ against the values in ‘year 2’. The correlation (R2 value) has been determined and is shown in the table below (the higher the R2 value the stronger the correlation).

 Variable Correlation (R2 value) Points 0.001 ± 0.096 SOTR 0.065 PDO 0.057

All of these values are so small they are statistically insignificant. In effect this means the performance of a team the year they are relegated from the premiership has basically zero predictive power when it comes to performance in the championship. That seems interesting to me, I’m very open to suggestions for the reason behind this as there’s not an obvious explanation I can think of.