Why PDO is Joe Kinnear’s friend

In an unexpected and somewhat bizarre move Newcastle have hired Joe Kinnear as their director of football. It comes at the end of a disappointing season for the Toon, who dropped from 5th in ’11-12 to finish 16th in ’12-13.

This fall-off was pretty well predicted by the shots models I used before the start of the season, yet still came as a surprise to some. The thing is Newcastle underlying numbers were no worse this season than last, and they were incredibly hard done by in terms of their sh% and sv%, pulling in a PDO of 907. As I suggested at the end of this post, if I were a manager I’d have my fingers crossed that a vacancy became available at St James’ because their terrible PDO almost guarantees Newcastle will be better the next time around. But is this necessarily true? Let’s take a closer look at their PDO, and see whether history suggests they’re likely to finish as low in the table in ’13-14.

In the prior 12 Premiership seasons, there have been 19 teams that have finished with a PDO between 887 and 927 (20 either side of Newcastle in ’12-13). Of those 19 teams, 8 were relegated, and 11 survived. As I’m interested in the season following a terrible PDO I’ll concentrate on the 11 teams that survived. Below is a table summarising the performance of the group in year 1 (when they had shockingly poor PDO’s) and year 2 (the year following). The values reported are the average of the group:

Screen Shot 2013-06-18 at 12.27.37 AM

Interestingly the underlying numbers of this group suggests they’re no better in year 1 than year 2 (I suspect score effects explain most, if not all, of the discrepancy). However ten of the eleven teams went on to pick up more points in year 2, and the same ten also finished in a higher league position the second time around.

So how can we explain these improvements? The answer lies in their PDO values. As a group the teams see their PDO regress 66% of the way towards the mean, which matches very nicely with the 62% season-to-season regression I’ve found in a much larger sample.

As director of football is Kinnear going to be directly responsible for an improvement in Newcastle’s save percentage (reanked 20th out of 20 in ’12/13) or their shooting percentage (ranked 17th out of 20 in ’12-13)? Almost certainly not. However it’s highly, highly, likely that they will regress in Newcastle’s favour, and Newcastle are almost guaranteed to get better results the moment Kinnear walks in the door. Correlation doesn’t mean causation, but Kinnear is going to get a good portion of the credit here, and were I a numbers-savvy member of the MSM who had confidence that this arrangement won’t blow up mid-season I’d be swimming against the tide and saying what a good appointment this is, then making sure to link back to that piece throughout the season. Kinnear could literally do nothing and Newcastle would still be almost guaranteed to record more points in ’13-14 than they did in ’12-13.


One thought on “Why PDO is Joe Kinnear’s friend

  1. Pingback: Why you should tell all your friends that Joe Kinnear will improve Newcastle | Counter Attack | Blogs | theScore.com

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