Here's a different way of looking at positive leverage. In the spirit of analyses that have looked at teams' ability to generate and take advantage of chances in a match, it's a way to identify teams that both generate positive leverage situations and manage to, well, leverage them for a win.
Here's what the graphs show. They depict teams' average positive leverage levels this season (on the x-axis) alongside their full-time win percentages. I have superimposed lines to divide the graph into four quadrants. The lines are league averages; so falling to the right on the x-axis (leverage) means the team is above average this year; falling above the y-axis (wins) means that the team has won more matches than the average team. Because leagues' averages and team performances differ, the lines fall in slightly different places for each of the leagues (Bundesliga, EPL, La Liga, and Serie A).
So the upper right hand quadrant contains teams that both generated leverage and converted it into wins. The lower right hand quadrant contains teams that generated leverage but did not convert it into as many wins. The upper left hand quadrant contains teams that did not generate much leverage but was able to convert it when they had the chance. And finally, the lower left hand quadrant contains teams that neither generated nor converted leverage when they had it.
So what do we see? Interestingly, each league has a different leverage profile. Take a look a the Bundesliga, for example. Clearly, the top 4 teams this year all populate the upper right hand (the "good") quadrant where teams generate leverage and convert it. In contrast, underperforming teams either don't generate leverage in the first place and fail to convert whatever measly leverage they have, or as is the case with Gladbach and especially Hoffenheim, they generate it, but fail to convert. Teams that are having a good season but are not contending for the title fall in the upper left quadrant: they don't generate as much leverage as the top teams, but they are about as good at converting (though no one can touch league leader Dortmund, it seems).
Compare this to the English Premiership, shown in the next graph, where generating and converting leverage seem to go hand in hand much more readily. That is, the teams that generate leads also are the ones that convert them, while teams that have a difficult time producing leverage also don't typically convert it to a win. One other thing of note: league leaders Arsenal and Manchester United are in a league of their own (and almost off the chart) in the far upper right hand corner. This stands in contrast to the Bundesliga, where the top 4 teams are more closely clustered together.
What about La Liga and Serie A - do we see similar patterns there? The next two graphs show both similarities and differences. La Liga looks more like the Premier League than the Bundesliga. For the better teams in La Liga, producing and converting leverage go hand in hand, though the relationship isn't as strong there as in England. A couple of other differences: Barcelona is yet again in a league of its own (forcing me to extend the x-axis scale to .7, as their ability to generate leverage is greater than anyone else's in Europe at the moment. One more thing: a good number of teams (eight altogether) fall into the underperforming quadrant in the lower left, suggesting a real imbalance in that league.
Finally, Serie A looks like a mix of leagues on these dimensions. It looks like La Liga and the EPL in that creating and converting convergence are correlated fairly highly, with the best teams in the upper right and the worst teams in the lower left quadrant (Lecce and Brescia are the only exceptions, looking a lot like Gladbach and Hoffenheim). At the same time, there is less clustering of teams. Thus, some teams really excel at generating leverage (Roma, Juventus, and Palermo), while others stand out primarily in their ability to convert (Napoli is an interesting example here, but also Inter and Lazio). AC Milan is good at both, so it's not a surprise they are where they are at the moment. And Bari, yet again, looks positively awful.
Soccer is often a game of pressure and leverage that one team exerts over another. Teams that are able to generate leverage and find a way to sustain it will win more often. What does this mean practically? It means, of course, that teams have to both find a way to exploit their opponent's weakness to go up a goal but then be tactically disciplined enough to sustain their advantage until time's up. As the graphs show, this year Dortmund, Manchester United & Arsenal, Barcelona, and AC Milan have been able to do so consistently over the course of their seasons.
