The blog has been quiet for a few days, and for a reason. I´ve been busy working on a little side project. Before too long, I´ll tell you more about that, but one of the things that have come of out of it has been a more detailed look at various performance indicators across leagues with better and more recent data. Without revealing too much, I thought the next graph was worth sharing, especially since I´ve been writing about efficiency ratios of teams in the big leagues of professional football in previous posts.
One of the more interesting facts - well, at least to me - has been that leagues produce remarkably similar overall yields (goals to shots ratios), right around .111 or 1 goal in 9 shots. These yields don´t vary all that much across years, suggesting that there is an inherent stability in this efficiency metric and one that hasn´t really changed very much, if at all, since the early days of notational analysis in football.
At the same time, it´s becoming ever more apparent that leagues produce this basic overall goal to shot ratio in very different ways. How different? Take a look at the graph below, which shows the overall yield (in green), along with accuracy (accurate shots to all shots) and conversion (goals to accurate shots) rates, based on data from individual matches collected over the past five seasons.*
As the graph shows, La Liga and Serie A are most similar to one another, combining high levels of conversion with low levels of accuracy efficiency. This means fewer accurate shots, but those that are accurate are more likely to find the back of the net. In contrast, Bundesliga shooters produce accurate shots more efficiently and are about as good when it comes to converting accurate shots to goals. The league that´s most different from the others is the Premiership. Efficiency metrics in England differ significantly, revealing very high levels of accuracy but also much lower levels of conversion efficiency. Premier League teams get to the same overall yield as teams in the other leagues by shooting more efficiently and scoring less efficiently. Why this is the case is anyone´s guess - and I invite (informed and well-intentioned) speculation in the comments! - but it does suggest that Premier League offenses and defenses play a somewhat different game than teams on the Continent.
* Recall that accuracy * conversion = yield.
One of the more interesting facts - well, at least to me - has been that leagues produce remarkably similar overall yields (goals to shots ratios), right around .111 or 1 goal in 9 shots. These yields don´t vary all that much across years, suggesting that there is an inherent stability in this efficiency metric and one that hasn´t really changed very much, if at all, since the early days of notational analysis in football.
At the same time, it´s becoming ever more apparent that leagues produce this basic overall goal to shot ratio in very different ways. How different? Take a look at the graph below, which shows the overall yield (in green), along with accuracy (accurate shots to all shots) and conversion (goals to accurate shots) rates, based on data from individual matches collected over the past five seasons.*
As the graph shows, La Liga and Serie A are most similar to one another, combining high levels of conversion with low levels of accuracy efficiency. This means fewer accurate shots, but those that are accurate are more likely to find the back of the net. In contrast, Bundesliga shooters produce accurate shots more efficiently and are about as good when it comes to converting accurate shots to goals. The league that´s most different from the others is the Premiership. Efficiency metrics in England differ significantly, revealing very high levels of accuracy but also much lower levels of conversion efficiency. Premier League teams get to the same overall yield as teams in the other leagues by shooting more efficiently and scoring less efficiently. Why this is the case is anyone´s guess - and I invite (informed and well-intentioned) speculation in the comments! - but it does suggest that Premier League offenses and defenses play a somewhat different game than teams on the Continent.
* Recall that accuracy * conversion = yield.
