Tuesday, November 11, 2014

On the impact of Bobby Zamora, Eduardo Vargas and Richard Dunne at QPR

The thoroughly entertaining Iain Macintosh today compiled an article suggesting how well QPR have been performing recently. He credits much of this resurgence to Harry Redknapp's re-utilisation of two senior Rangers, Bobby Zamora and Richard Dunne.

While he is of course correct - especially in a poetic sense - a certain set of numbers emerging from my ever-expanding Player Plus/Minus dataset - which you can find by clicking here - might help quantify the effect Zamora and Dunne have both have on the Hoops.

In their eleven matches so far, the Rs have managed a goal difference of -11, or being outscored by one goal for every 90 minutes they take the field. This means any player who has managed each of the 990 minutes Rangers played so far this season will have an Individual Plus/Minus of -11. If you will, think of Individual Plus/Minus as a player's "personal" goal difference, or the amount of goals his team concedes while he's on the field, subtracted from those his team scores when he plays.

However, players rarely play every minute of every match of the Premier League season - in fact, in last year's abbreviated (four-team) sample, only Brad Guzan and Steven Caulker managed such a feat. This means to compare a player to his teammates and thereby examine his impact on his club, we must standardize the time-frame in which player and team both score and concede. That is, a team's Goal Difference divided by 38 results in the average amount they score/concede more than their opponents per match - so a Player's Plus/Minus rating per 90 minutes allows us to compare a team's performance when a certain player is deployed against when he is not.

But technical definitions aside, this set of information details how much a team scores or concedes over 90 minutes when a player is on the field. And Zamora's, particularly, numbers are spectacular. When he is on the field, QPR have a Goal Difference per game of 0, a full goal-per-game improved over when he doesn't take the park. 

This is the single best "Impact Factor" for a forward in the league, and is shared (with teammate Yun Suk-Young) for the third-best rating of any position. Only Jack Cork and Charles N'Zogbia are better throughout the entire league; another Ranger with a similarly lofty total is forward Eduardo Vargas, whose Impact rating of +0.803 is fifth-best.

Dunne, the other cartworkhorse whose virtues Macintosh espouses, rates as the seventeenth-most impactful defender in the league of the 95 that qualified (must have played at least 360 minutes).

Other interesting points to come out of the data set include Adnan Januzaj's lack of ability to influence proceedings for Manchester United (with the Reds 0.71 goals per 90 minutes worse off with him on the field), Jack Wilshere's awful start to the campaign (Arsenal are nearly 1.7 goals worse-off with him playing, the worst ratio in the EPL) and the absolute ostrich egg laid by France forward Emmanuel Riviere.

For more information - and some pretty, relatively-informative charts - on Player Plus/Minus, you can read the primer here, or search this site for "Plus/Minus".

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