Introducing a new statistic to measure a goal scorer’s efficiency

Kenny Miller, courtesy of RFC

written by – Rangers Report

While measuring an attacking player’s effectiveness, it has become the norm to move away from just looking at his final goal tally & has shifted to relying more on a players goal scoring ratio per 90 minutes.  Additionally, many are moving away from calculating penalty goals in a player’s data & relying more on Non-Penalty Goals per 90.

Jimmy Coverdale covered this shift in emphasis while evaluating the top goal scorers in the English Premier League last season in Stats Insights article.

The next step in this statistical evolution may be to evaluate a players’ production based on how much his team actually possesses the ball.   (Full disclosure:  These analytics are based on some ideas that North Yard Analytics’ Dan Altman discussed in his short series of videos on YouTube).  

While evaluating a player based on a per 90 minutes ratio is much more valuable then simply looking at final totals – what if a player plays on a bad team?  What if his team possesses the ball 45% of the game compared to another player whose team has the ball 60% of the game?

What if two players both score fifteen goals & play roughly the same amount of minutes – but one player plays for a team that dominates possession while the other plays for a poor side that struggles to sustain any possession of the ball whatsoever.  If you were scouting the two players, you’d obviously study them both, but it should be taken into account that one player saw much less of the ball but still managed to score the same amount of times as his peer & may be more efficient in his ability to score.

So, rather then assessing a forward based on 90 minutes, Goal Scoring Efficiency Rating (GSER) looks at the goalscoring rate for how many minutes his team hypothetically possessed the ball.  (Keep in mind that the possession statistics for each player are not exact.  They are for an entire match & often the player does not play the full 90 minutes – so there is a definite margin of error).

Let’s look at Calum Gallagher’s production last season while on loan with Cowdenbeath, as an example & compare it with Kenny Miller’s stats – also from 2014-15.

In Gallagher’s 770 minutes played, Cowdenbeath only possessed the ball for 354 of those minutes.  He scored five goals in those 354 minutes giving him a Goal Scoring Efficiency Rating of 0.014.

Rangers possessed the ball for 1,050 of the 1,875 minutes that Kenny Miller played.  Miller scored seven goals in those 1,050 minutes leading to a GSER of 0.007.  That’s half of Gallagher’s rating.  If you applied Gallagher’s Goal Scoring Efficiency Rating to those same minutes he would have hypothetically scored 14 goals.

Cameron Howieson, courtesy of Graham Stuart (Reuters)

Here are the leaders in Goal Scoring Efficiency Rating so far in the Scottish Championship.  Two games is not enough to do any serious analysis of these stats, rather this is just providing a snapshot of how GSER works.  Note:  only players who have played at least 60 minutes were considered.

Team Games Min Goals G/90 Team Possession GSER
Cameron Howieson St Mirren 1 67 1 0.37 0.37 0.040
Kenny Miller Rangers 1 90 2 0.71 0.71 0.031
Willie Gibson Dumbarton 2 179 2 0.89 0.45 0.025
Iain Russell Queen of the South 2 176 2 1.01 0.51 0.023
Iain Flannigan Alloa Athletic 1 90 1 0.51 0.51 0.022
Michael Chopra Alloa Athletic 2 135 1 0.80 0.40 0.019
Lee Wallace Rangers 2 180 2 1.34 0.67 0.017
Jason Cummings Hibs 2 102 1 1.20 0.60 0.016
Ryan McCord Raith Rovers 2 136 1 0.90 0.45 0.016

There obviously is a margin of error given that the leader, Cameron Howieson has not played a full match & we have no way of knowing St. Mirren’s possession for those 67 minutes compared to the full 90 minutes.  However, if these numbers were hypothetically for more games, let’s say it’s half the season & a team was looking to make a January signing to impact their offensive output…Howieson should be flagged for further scouting regardless of the margin of error.

Dumbarton’s Willie Gibson is another player you would take note of (if this was a larger sample side) as a player whose goal scoring rate is more impressive given that his team possesses the ball less then his peers, the same with Michael Chopra – who scored for Alloa against Rangers this past week.

It all feels very Moneyball – but if you were a small club looking to find diamonds in the rough (sorry for the cliche) this may be one of the measures you Could use to identify players to take a closer look at.

You can follow Rangers Report on Twitter @TheGersReport

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