A companion to Ted Knutson’s piece on Jordan Rhodes

Ted Knutson wrote a piece earlier looking at the translation of goal scoring for players that have moved between the Championship and the Premiership since 2005. He found that the group of players lost an average of ~20% of their goals per game in the move up to a tougher league.

This is something I’ve looked at previously at the team level and, despite the lack of data available to Ted, and inherent problems within it, our numbers aren’t incredibly different – I came to the conclusion that teams promoted to the Premiership score ~35% fewer goals than they had in the Championship.

I also went a step further and did the same study for each of the promotion/relegations from the Premiership down to league two in order to come up with the the comparative strength of the four English leagues. One of the summary tables from that work is reproduced below:

Screen Shot 2013-06-05 at 8.13.14 AM

The main focus of concentration in Ted’s article is Jordan Rhodes, so I want to go back and test these numbers to see how well they’d have predicted his progression as he moved up through the divisions. First, courtesy of Ted’s post, here are his counting numbers over that time.

Screen Shot 2013-06-05 at 7.51.32 AM

So his goals per game dipped a little in the transition to league one (which may also be due to the small sample in his ‘age 19’ season), and steadily improves until he once again moves up a division, this time to the Championship. So for each of those league transitions how many goals would he have been predicted to score based on his performance the last time around?

Screen Shot 2013-06-05 at 8.20.58 AM

And you know what, they’re pretty good estimations – one is spot on (which undoubtedly requires a slice of luck on my behalf), and the other is within 15%. Given these expected values take nothing into account in terms of a players improvement as they gets older (few players peak at 19), their style of play, or the team they’re being transferred to I think this is a pretty respectable start. Not to say this would be the case for every player, but I have some confidence that these are pretty decent ball-park estimations.

Finally, Ted suggests that a Premiership club should have purchased Rhodes in each one of the prior summers. Assuming they’d done so, and he’d started each Premiership game, what would these numbers predict his goal scoring tallies to have looked like?

Screen Shot 2013-06-05 at 8.08.30 AM

And that seems pretty sensible – goal scoring increases with age as the player develops. It would also have been a damn impressive start to a career – I doubt there are many 23 year olds with 50+ Premiership goals under their belt.

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