We're right in the middle of the summer transfer season. Lots of rumors swirling about, and scouts driven to distraction by the demands of coaches, agents, and executives to provide quick and reliable information about a player's performance and worth.
In a global market for players, many of the potential transfers involve the proposal to move a player from one league to another. So clubs want to be able to evaluate a player's performance in leagues as different as Brazil's Serie A, Germany's 2. Bundesliga, or the Eredivisie. Unfortunately, a basic question like "How much is a goal in the Eredivisie worth, compared to one in the Bundesliga or the Premiership?" is difficult to answer. Because football is a team sport, an individual's performance in the past has to be tied to the performance of a team (or even just a subset of the team) and in any given match. What's more, any prognostications about a player's future performance involves predictions about his play in and with the new team against a new and different set of opponents.
All this means that knowing that Falcao scored 16 goals in the Portuguese league last year or that Luis Suarez scored 35 for Ajax in 2009/10 doesn't tell us how many goals these players would score in La Liga or the Premiership. We suspect fewer, but how many fewer is the question that really matters. That depends on what we think makes someone score a lot or just a few in the first place, and this is where the devil is in the details. After all, there are at least three factors at work - the player's quality, the team he plays on, and the league he plays in (i.e., the teams he played against). Ignoring the first two for a second, let's take a look a league characteristics.
From what I can tell, when comparing player performance across leagues, most people most of the time look at overall league quality. This makes lots of sense since we want to know the level of competition a player faces. When playing in or moving to a better league, scoring should be harder, on average, because defenders and goalkeepers will be of higher quality. So clearly, league quality will help us put a "Bundesliga number" on Falcao's Portuguese goals.
But my hunch is that that's not the end of the story and that other characteristics of leagues come into play as well. Some of these are harder to quantify than others - a country's culture and environment, tactical preferences of coaches, differences in stadiums or playing times, or frequency of matches. Perhaps one of the things that are more straightforward to put a number on is how balanced a league is.
While the overall "quality" of a league (however we may think of this thing "quality) should affect technical and physical aspects of playing, league balance, for example, may also affect the psychology of a match or a team. In particular, teams playing in a more balanced league may have greater faith that they have a shot at winning the match on any given day, or turning around a match when they're down a goal or two. Teams and players on both sides of the ball in more imbalanced leagues may have more and less confidence that the match will yield the desired outcome. We can imagine that this can shape any number of things like a team's tactical behavior or individual players' levels of effort.
So aside from affecting league revenue - a problem long been recognized by sports economists - parity could also matter for identifying talent. While league quality should affect how well players perform, parity could affect how they play the game. But before I get too far into the weeds of team strategy and sports psychology, I was wondering what the universe of the top leagues actually looks like when we put these two dimensions - quality and balance - together.
For illustration, below is a graph of league quality (measured by the 2009/10 UEFA coefficient) and league parity (measured by the wins Gini coefficient I used previously, calculated from data for the same season) using data for six leagues that I collected with the help of Benjamin Leinwand. Remember that a higher number on quality indicates a better league, and a higher number on the Gini indicates a more imbalanced league.
1. Higher quality / higher imbalance leagues: the EPL and La Liga
2. Higher quality / lower imbalance leagues: the Bundesliga
3. Lower quality / lower imbalance leagues: Ligue 1, Serie A
In a global market for players, many of the potential transfers involve the proposal to move a player from one league to another. So clubs want to be able to evaluate a player's performance in leagues as different as Brazil's Serie A, Germany's 2. Bundesliga, or the Eredivisie. Unfortunately, a basic question like "How much is a goal in the Eredivisie worth, compared to one in the Bundesliga or the Premiership?" is difficult to answer. Because football is a team sport, an individual's performance in the past has to be tied to the performance of a team (or even just a subset of the team) and in any given match. What's more, any prognostications about a player's future performance involves predictions about his play in and with the new team against a new and different set of opponents.All this means that knowing that Falcao scored 16 goals in the Portuguese league last year or that Luis Suarez scored 35 for Ajax in 2009/10 doesn't tell us how many goals these players would score in La Liga or the Premiership. We suspect fewer, but how many fewer is the question that really matters. That depends on what we think makes someone score a lot or just a few in the first place, and this is where the devil is in the details. After all, there are at least three factors at work - the player's quality, the team he plays on, and the league he plays in (i.e., the teams he played against). Ignoring the first two for a second, let's take a look a league characteristics.
From what I can tell, when comparing player performance across leagues, most people most of the time look at overall league quality. This makes lots of sense since we want to know the level of competition a player faces. When playing in or moving to a better league, scoring should be harder, on average, because defenders and goalkeepers will be of higher quality. So clearly, league quality will help us put a "Bundesliga number" on Falcao's Portuguese goals.
But my hunch is that that's not the end of the story and that other characteristics of leagues come into play as well. Some of these are harder to quantify than others - a country's culture and environment, tactical preferences of coaches, differences in stadiums or playing times, or frequency of matches. Perhaps one of the things that are more straightforward to put a number on is how balanced a league is.
While the overall "quality" of a league (however we may think of this thing "quality) should affect technical and physical aspects of playing, league balance, for example, may also affect the psychology of a match or a team. In particular, teams playing in a more balanced league may have greater faith that they have a shot at winning the match on any given day, or turning around a match when they're down a goal or two. Teams and players on both sides of the ball in more imbalanced leagues may have more and less confidence that the match will yield the desired outcome. We can imagine that this can shape any number of things like a team's tactical behavior or individual players' levels of effort.
So aside from affecting league revenue - a problem long been recognized by sports economists - parity could also matter for identifying talent. While league quality should affect how well players perform, parity could affect how they play the game. But before I get too far into the weeds of team strategy and sports psychology, I was wondering what the universe of the top leagues actually looks like when we put these two dimensions - quality and balance - together.
For illustration, below is a graph of league quality (measured by the 2009/10 UEFA coefficient) and league parity (measured by the wins Gini coefficient I used previously, calculated from data for the same season) using data for six leagues that I collected with the help of Benjamin Leinwand. Remember that a higher number on quality indicates a better league, and a higher number on the Gini indicates a more imbalanced league.
Clearly, quality and balance don't necessarily go hand in hand. While the Eredivisie is the lowest quality and most unequal of the six, the other five spread out in interesting ways. When we remove the clear outlier of the group - the Eredivisie - from the graph, things come into focus. Take a look.
This leaves us with three types of leagues (relatively speaking, of course):
1. Higher quality / higher imbalance leagues: the EPL and La Liga
2. Higher quality / lower imbalance leagues: the Bundesliga
3. Lower quality / lower imbalance leagues: Ligue 1, Serie A
It seems that the Bundesliga - financially the healthiest of the five leagues - currently has the best of both worlds, providing competitive balance and a high level of play. But if you asked most fans and observers, they would tell you that you see better, more entertaining football in La Liga and the Premiership. I don't necessarily agree - anyone watching Dortmund last year knows why - but it seems that the path to "better" may come at the expense of "more unequal." I don't want to make too much of these graphs - they're mostly meant for illustration, and of course, leagues' positions will change somewhat over time, as the other analyses of league balance have shown.
But to the extent that teams and players are contending with the league environment, I bet it matters whether you are playing in a lower quality balanced league or a higher quality imbalanced one. Perhaps teams will give up more easily when falling behind in La Liga and the Premiership, or perhaps play harder to avoid falling behind in the first place. And scoring lots of 3rd and 4th goals in a match may be easier for a team like Ajax in a league like the Eredivisie where lesser teams might make less of an effort after falling behind. Right now, this is idle speculation, but I hope to put some of these ideas to the test before too long.
None of this means, by the way, that Liverpool shouldn't have bought Suarez - I think he's been a great player to trade for (since it also solved the Torres problem for the club). In the meantime, as you watch the transfer market unfold this summer, keep in mind that there is more to understanding a player's quality than knowing how good the league is he has been playing in. And clubs better watch out to draw the right conclusion from the performance indicators they're looking at.
But to the extent that teams and players are contending with the league environment, I bet it matters whether you are playing in a lower quality balanced league or a higher quality imbalanced one. Perhaps teams will give up more easily when falling behind in La Liga and the Premiership, or perhaps play harder to avoid falling behind in the first place. And scoring lots of 3rd and 4th goals in a match may be easier for a team like Ajax in a league like the Eredivisie where lesser teams might make less of an effort after falling behind. Right now, this is idle speculation, but I hope to put some of these ideas to the test before too long.
None of this means, by the way, that Liverpool shouldn't have bought Suarez - I think he's been a great player to trade for (since it also solved the Torres problem for the club). In the meantime, as you watch the transfer market unfold this summer, keep in mind that there is more to understanding a player's quality than knowing how good the league is he has been playing in. And clubs better watch out to draw the right conclusion from the performance indicators they're looking at.
