Premier League 2011-12: Player Impacts – discussion

In previous posts I have tested different ways of rating players using Opta data to mark out key fields for each major position which correlate positively to points.  The summary of these reviews can be read here.

What troubled me about some of the findings in this process was the underperformance of some high-profile players whose strengths were clearly not rewarded by the analysis. For example, Ashley Cole, Theo Walcott, and even Fabricio Coloccini – who actually made the PFA Team of the Year last season. Although I’m pretty keen to separate subjective opinion from raw data analysis, in particular the presence of Coloccini in the PFA Team of the Year – voted for by fellow professionals – cannot be disregarded lightly. Not to mention his superb performance at the weekend!

So in this series of posts I have published another ‘view’ of footballers – this time looking at team performance in the league with and without a particular player in the starting line-up. This can be used as a simple indicator regarding which players’ presence helps/detracts from their team. I used Tableau Public for the first time for this, and had some teething issues attaching my graphs/tables, so they are shown in separate posts below.

Method

I calculated the average points gained, team goals scored and team goals conceded for every team and player and compared this to the team averages without that player in the starting line-up. Of course, those who started every game don’t have a ‘without’ average so I removed players who started every game. In addition, I took out players who started fewer than 4 games, and players who started more than 34 games. I did this on a whim after I saw that Robin van Persie had a negative impact to Arsenal’s points average – this happened because he started 37 games for Arsenal last season, and in the 1 game he didn’t start Arsenal won against Stoke. This annoyingly made Arsenal’s points average without RVP as 3pts per game, which is a bit ridiculous when he came off the bench and scored 2 in that game anyway! Players with 1 start had a similar problem, as the result of that game determined their impact. That example serves a purpose in explaining the limitations of a data table like the one below, even though the bias is reduced by increasing the min/max number of starts to 4 and 34. Of course if a player started in 34 games but the 4 he missed were away visits to Man City, Man Utd, Arsenal and Spurs then again his points average is more likely than not to be a little too high.

All the impacts below need to be taken with a pinch of salt but information is power, and I think this review is complementary to my previous player analyses and will help to give a better profile of players and their contribution to team performance. Incidentally, in this review Coloccini didn’t qualify because he started 35 games last season.

Hopefully, the tables/graphs are self-explanatory, but here are some highlights:

  • Adebayor for Spurs had the biggest positive effect on points for any team, followed by Arteta for Arsenal
  • Theo Walcott and Ashley Cole both had a strong positive effect for Arsenal and Chelsea respectively despite the poor stats analysis rating in previous posts
  • Notable ‘unlucky mascots’ for their teams were Berbatov for Man U and Ramsey and Arshavin for Arsenal
  • Swansea had a comparatively short range of differences between their players, which shows not only that they were able to field a remarkably consistent team for much of the season, but also perhaps indicates that no matter who was in the starting line-up, the player positions and tactics were relatively easy to substitute
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3 thoughts on “Premier League 2011-12: Player Impacts – discussion

  1. Pingback: Premier League 2011-12: Player Impacts – average points | thepowerof11

  2. Pingback: Premier League 2011-12: Player Impacts – goals for & conceded | thepowerof11

  3. Pingback: Premier League 2011-12: Player Impacts – data | thepowerof11

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