http://www.zonalmarking.net/2012/05/04/the-relationship-between-possession-and-shots/
The Relationship Between Possession and Shots
May 4, 2012

The graph below shows the relationship between average possession per game (along the bottom) and shots per game (along the side) for the 98 sides in the Premier League, Serie A, Ligue 1, La Liga and the Bundesliga.



All data is taken from the excellent WhoScored website.

As you might expect, there’s a fairly obvious correlation – the more possession you have, the more shots on goal you’re likely to attempt, which is hardly a revelation.

The graph is interesting, however, for two reasons. First, because there are clear differences between the five separate leagues. Second, because there’s a handful of sides that don’t fit the pattern, and a lot of variation amongst the sides who see a lot possession.

The sides who are significantly ‘higher’ on the graph compared to the line of best fit are particularly efficient with possession – they have more shots than you’d expect for the amount of the ball they enjoy. Those who are significantly ‘lower’ are less efficient – they see a lot of the ball but record relatively few shots on goal.

Of course, being more or less efficient is not necessarily ‘better’ – because the sole purpose of possession is not to score a goal. Possession can be used as a defensive tactic to play out time when a side is ahead, and can be used to tire the opposition, before attacking more directly later on. The intention here is not to ‘rank’ sides, but to show their different styles.

Here’s a similar graph breaking the 98 sides into their five respective leagues:


The most interesting pattern here is the Premier League, because so many sides are on the more direct side of things. Swansea, the black dot towards the bottom-right corner, are unique within the division, which explains why there’s been so much discussion of their patient passing game.

A line of best fit for each league also shows the differences:


But what about individual teams? Here, some sides are significantly higher or lower than what we’d consider standard. The most efficient sides average one shot from every 3% of possession, the least efficient teams need 5% to have an attempt.

The most efficient sides are (graph below):


Also of interest are QPR (horizontal stripes) and West Brom (vertical stripes), who both record significantly more shots than you’d expect for their average possession.



The ‘least efficient’ sides are:

1. Ajaccio – the dark blue dot
2. Koln – the green dot
3. Swansea – the orange dot
4. Evian – the purple dot
5. Athletic Bilbao – the red-and-white striped dot

Also of interest are those higher up the possession scale – Bayern Munich are the red dot, Barcelona are the red-and-blue striped dot.

Again, the purpose is not to indicate that a particular style is better – simply that there are big variations. Swansea see more possession than Manchester City, yet have six fewer shots per game. Manchester United have as many shots as Barcelona, despite 12% less possession per game.

In general, more possession will mean more shots – but it’s not always the case.