Soccer's relatively low scores compared to other team sports make the game exciting and agonizing at the same time. After all, any one score, any one action or mistake on the field can make or break a team's day. Soccer's high stakes and the rare beauty of goals have a downside for analysts, however. In particular, the infrequency of goals from an analysis perspective means that random chance is likely to play a larger role in determining goals than in events that occur more often.
What to do? In a sport where the outcomes that count are rare, it makes sense to analyze those aspects of the game that lead to those outcomes and that have the convenient property of being more common. Enter shots, since they are most proximate to the thing that matters most but that's also the most elusive. Shots also lend themselves more easily to statistical analysis, and I have looked at shots from a variety of angles over the last few months, using data from different leagues (click here for a list).
We can think about the role that shots play in a couple of different ways. A useful framework for understanding the role of shots for shaping goal creation is StatDNA's description of how goals are linked to shots. This framework conceptualizes goals as a combined function of the number of shots and the quality of shots. Another way to think about this to say that we need to think about the quantity and quality of shots.
Before we can get to the question of what kinds of shots are more likely to yield goals, however, we need to understand the origins of the different kinds of shots teams actually take. To get a handle on this, I collected data on shot creation by Premier League teams in the first half of the 2010-11 season (based on data from the Opta-powered Guardian chalkboards). The categories are straightforward: shots are classified by whether they originated from open play, free kicks, fast breaks, penalties, or corners.
So here are the average numbers of shots, split up by shot types for the league as a whole.
On average, teams took 14.7 shots per match in the first half of the season. That's slightly higher than the long-run average of the league, but not by much (the avg. is around 12-13 per team and match). What's more interesting is how these shots were distributed. The most common shots were generated from open play (11), followed far behind by shots from corners (2.1), free kicks (.82), fast breaks (.52), and finally, penalty kicks (.14).
Here's another way to look at these numbers. Rather than looking at the overall number of shots, this pie chart shows the relative proportions of each shot type relative to all shots taken.
Clearly, different teams generate shots differently. While all teams generate more shots from open play than any other situation, the extent to which they rely on open play varies.
Compare Tottenham and West Ham, for example. While Spurs generated 70% of all shots from open play 78% of all shots West Ham took came from open play. Or consider corners: while 17.4% of all Tottenham shots were generated in the aftermath of corners (Peter Crouch anyone?), only 8.5% of Wigan's were. And check out Wolves: they led the league with 1 in 5 shots generated off corners - 19.2%). Speaking of Wolves, they have an unusual distribution of shots in that they basically generate all of their shots from open play or corners (for a combined 94.7% of al shots).
Finally, compare Liverpool's and Bolton's reliance on free kicks: while only 3.5% of all Liverpool shots came from free kicks, over 9% of Bolton's did.
Since you typically can't score unless you shoot first, shots are central to understanding goals. Shooters in the Premier League are among the best in the world (and certainly among the most accurate in Europe), so I'll dig a little deeper into EPL shot creation over the next few weeks to see if certain types of shots are more likely to be on target, and how different kinds of shots are related to goals.
What to do? In a sport where the outcomes that count are rare, it makes sense to analyze those aspects of the game that lead to those outcomes and that have the convenient property of being more common. Enter shots, since they are most proximate to the thing that matters most but that's also the most elusive. Shots also lend themselves more easily to statistical analysis, and I have looked at shots from a variety of angles over the last few months, using data from different leagues (click here for a list).
We can think about the role that shots play in a couple of different ways. A useful framework for understanding the role of shots for shaping goal creation is StatDNA's description of how goals are linked to shots. This framework conceptualizes goals as a combined function of the number of shots and the quality of shots. Another way to think about this to say that we need to think about the quantity and quality of shots.
Before we can get to the question of what kinds of shots are more likely to yield goals, however, we need to understand the origins of the different kinds of shots teams actually take. To get a handle on this, I collected data on shot creation by Premier League teams in the first half of the 2010-11 season (based on data from the Opta-powered Guardian chalkboards). The categories are straightforward: shots are classified by whether they originated from open play, free kicks, fast breaks, penalties, or corners.
So here are the average numbers of shots, split up by shot types for the league as a whole.
On average, teams took 14.7 shots per match in the first half of the season. That's slightly higher than the long-run average of the league, but not by much (the avg. is around 12-13 per team and match). What's more interesting is how these shots were distributed. The most common shots were generated from open play (11), followed far behind by shots from corners (2.1), free kicks (.82), fast breaks (.52), and finally, penalty kicks (.14).
Here's another way to look at these numbers. Rather than looking at the overall number of shots, this pie chart shows the relative proportions of each shot type relative to all shots taken.
This chart demonstrates very nicely how common shots created from open play, and how truly uncommon penalties are, all things considered. 75% of all shots come from open play, less than 1% result from penalties. About 15% of all shots result from corners; about 5% from free kicks, and another 3.5% from transitions. Combined, shots created from open play and corners account for 90% of all shots taken.
Of course, as always, these are league averages, and averages can hide interesting variations. They do in this case, too. For example, take a look at shot distributions separately for each team.
Compare Tottenham and West Ham, for example. While Spurs generated 70% of all shots from open play 78% of all shots West Ham took came from open play. Or consider corners: while 17.4% of all Tottenham shots were generated in the aftermath of corners (Peter Crouch anyone?), only 8.5% of Wigan's were. And check out Wolves: they led the league with 1 in 5 shots generated off corners - 19.2%). Speaking of Wolves, they have an unusual distribution of shots in that they basically generate all of their shots from open play or corners (for a combined 94.7% of al shots).
Finally, compare Liverpool's and Bolton's reliance on free kicks: while only 3.5% of all Liverpool shots came from free kicks, over 9% of Bolton's did.
Since you typically can't score unless you shoot first, shots are central to understanding goals. Shooters in the Premier League are among the best in the world (and certainly among the most accurate in Europe), so I'll dig a little deeper into EPL shot creation over the next few weeks to see if certain types of shots are more likely to be on target, and how different kinds of shots are related to goals.
