Previously I’ve written about examining conversion rates and shots as a way of examining which areas an offense or defense excels at or is struggling with. Shots can be a crude estimation for opportunities and conversion rate and estimation of how well a team executes on those opportunities. I had looked at offense and defense separately in the past, but decided to combine the two to see if any interesting patterns emerged. I represented the difference as a vector, with the magnitude (length of the line) representing how much of an advantage a team had and the angle representing how much opportunities or execution contributed to that advantage. Since one of the emerging stories of the season is the high number of shots Manchester United is conceding, I thought it would be interesting to see how this season stacks up compared to the previous season.
All matches for the 2011/2012 and 2010/2011 season.
The color of each team’s line is scaled to the number of points (red is the lowest, blue highest). In the 2010/2011 season, the best teams had a considerable advantage in both Shot Differential and Conversion Rate Differential. For the 2011/2012 season, a similar pattern is emerging although some successful teams have a negative shot differential. Manchester United has a negative shot differential however they have an incredible advantage when it comes to conversion rate. Not only are they taking advantage of the opportunities they create, but somehow they are also preventing their opponents from finishing their chances. The quality of the shot opportunity isn’t taken into consideration here so it’s possible Manchester United isn’t allowing their opponents to get in to good positions. Arsenal, who have gotten off to a slow start, have a much lower conversion rate differential than last year.
Wins for the 2011/2012 and 2010/2011 season
Looking at just wins, last year most of the poorly performing teams had a negative shot differential, while the more successful teams all had a positive one. All teams had a positive conversion rate differential for victories which is not surprising.
Ties for the 2011/2012 and 2010/2011 season
Looking at ties, in the previous season, most good teams had a positive shot differential, but a negative conversion rate difference. The opposite was true for most of the weaker teams.
Losses for the 2011/2012 and 2010/2011 season
And finally, looking at losses, a similar patterns to wins is evident, with more successful teams retaining their positive shot differential and less successful teams with a negative shot differential.
The good news for Arsenal is that even though the season has gotten off to a great start, the metrics look like they are doing alright and hopefully it is just a matter of time until they turn it around.
