player_churn_league_2

For those who weren’t aware, Ben Mayhew (of @experimental361) and I now both form part of the Press Association’s product development team, combining our respective powers to come up with data and graphical innovations, with football very much part of our remit. There are quite a lot of ideas flying around the office which don’t immediately find their way into our products but which at least one of us will doggedly insist is worth pursuing, so we’ve decided to start developing some of these between us.

Here we have the first part of our first such collaboration, born out of a discussion around squad ‘churn’ across the Football League. Having endured the traditional summer babble around transfers we wanted to understand to what extent squads had actually evolved over the summer and whether there were any interesting patterns here. Have the promoted and relegated sides experienced more player turnover as they strengthen and downsize respectively? Who’s been able to keep the core of their squad together and does this get trickier as you move down the divisions?

On the eve of the Football League season we’ve produced a graphic for this season’s League 2 teams, to be followed by versions for the other English divisions, up to and including Premier League, in due course.

First of all we came up with a headline measure for continuity: of all the minutes played across a club’s squad in league matches last season, what percentage were accumulated by players who are still at the club? This gives us a more reliable measure than just counting players, as it will be dented more by a first team regular leaving than by the departure of a fringe player.

We also wanted to see what else we could get into our graphic without cluttering it and decided to look at to what extent each club relied on a core of players. We counted how many players had represented their clubs for at least 25% of possible league minutes, which felt like a sensible definition of a ‘first team’ player. Counting how many players met this criterion for each club gives us a useful measure of squad rotation and we can also count how many of these have remained at the club.

Finally we added in a measure of what percentage of the club’s total league minutes had been accumulated by their 11 most-used players last season, which gives us a different way of looking at how much or little each manager rotated their squad.

 

Observations:

  • What’s really interesting here is the teams relegated from League 1. 3 of the 4 teams that came down have jettisoned the bulk of their squads over the summer – with Bury’s team virtually unrecognisable – while the 4th, Hartlepool, have only moved on 4 of their first team regulars from last season.
  • Despite surviving on goal difference last season, Dagenham & Redbridge’s line-up is the most similar to that of their previous campaign.
  • Wimbledon and Portsmouth’s heavy personnel changes and use of short-term deals during 2012/13 are evident here – their most-used players racked up a significantly smaller proportion of the clubs’ pitch minutes and many have since moved on.

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