Shooting is obviously an important component of a football game. The best teams spend more time near their opponents goal, take more shots and score more goals. But are the extra goals explained by their larger volume of shots take or do they score a larger proportion of the shots they take? Below is a plot of team shooting percentage against the teams shots on target ratio where SOTR=STF/(STF+STA)*
The correlation is almost non existent. As a teams SOTR increases so does its shooting percentage but only marginally, and the correlation is so poor that the effect is very unpredictable. Team shooting percentage in the premiership can be defined by the following curve
That is a pretty wide spread. Using standard deviation, roughly three teams a season will be more than one standard deviation from the mean, with another three teams more than one standard deviation below the mean. This can have a big effect has on an average premiership team
The effect is large, almost 10 goals for an average team. This is a simplistic way of looking at it but 10 goals are worth ~6.4 points in the standings. And this is for teams who take an average number of shots. It’s easy to see a better team that generates a higher volume of shots losing out on a European place or even winning the league courtesy of a poor Sh%.
Finally here’s a table of the ten best and worst seasons in terms of shooting percentage
|2001-02||Manchester United||33.98||2007-08||Derby County||10.99|
|2001-02||Arsenal||30.27||2008-09||West Bromwich Albion||14.12|
|2005-06||West Ham United||30.09||2005-06||Sunderland||14.21|
|2000-01||Manchester United||29.92||2006-07||Manchester City||14.29|
There must have been something in the water in 2001-02. Looking at shot totals I don’t think they were counting very rigorously that season so that may explain it (or maybe ‘shot on target’ was redefined beginning in 03?). A special mention goes to Sunderland who appear in the ‘worst’ column three times!
Next time I’ll go on to look at save percentage and see if whether the observations of shots hold true for defence.
*I’m using shots on target for a couple of reasons. The main one is that it is (almost) completely independent of shooting percentage whereas a points or goals are much more dependent. It also gives a good indication of how dominant a team is (it stands to reason that better teams are more dominant and therefore generate a larger proportion of shots on target). STF = shots on target for and STA = shots on target against