When FC Twente played Benfica Lisbon to a 2-2 draw on Tuesday night, Tottenham manager Harry Redknapp was in the stands to witness it. Mind you, 'Arry wasn't just out for a fun night of European football in Enschede - he was there to take a personal look at Bryan Ruiz, Twente's Costa Rican striker and a target for Spurs in this summer's transfer window. Ruiz has done well since joining the Dutch team, and clearly is a very talented and multidimensional player who's worth a look and has attracted serious enough attention for Redknapp to make the trek to the Netherlands.The story of Redknapp and Ruiz is not an exception, though. As Thomas Boeschoten from catenaccio.nl points out in a recent article, English and Italian clubs have been spending the most money during the current transfer window. And while English clubs have been losing the most money from transfers, Dutch clubs have been making the biggest profits from the sales of players. In numbers, English clubs have spent about 365 million euros, while taking in about 195 million (not including the most recent Fabregas transfer). As Boeschoten rightly notes, the Dutch league has become essentially a minor league to the Premiership.
One interesting question for managers and scouts, of course, is how to evaluate performance in that league. As we have noted before, it is not entirely clear how best to evaluate a player's performance in leagues as different as Brazil's Serie A, Germany's 2. Bundesliga, or the Eredivisie. In part, it is difficult to compare 10 goals scored in the Netherlands with 10 goals scored elsewhere because of differences in league quality and league balance. In highly unequal leagues - and the Eredivisie is a lower quality league and also one of the more unequal ones - strikers like Luis Suarez or Bryan Ruiz may have an easier time standing out, especially against the lesser teams, and this may result in a higher fee than may be warranted.
All of this got me to thinking about the connection between offensive production and league balance. My hunch was that average scores should be higher in the more unequal leagues where we should see more blowouts and where the better teams are able to add a 3rd or 4th goal more easily than elsewhere.
So the analysis question is this: is there a connection between goals and inequality in a league? To answer that question, I went back to the data collected with Benjamin Leinwand for the the last 15 seasons across six European leagues. Below is a graph of a league's level of parity - measured with the help of the Gini coefficient for points - and the average number of goals per match, along with a linear trend line with the best fit to the data. Recall that a higher Gini value indicates a less balanced league.
While it's clear that there is a fair amount of variability, it's also clear that there is a positive relationship between imbalance and scoring, and it's statistically significant. Scoring is higher in leagues that are more imbalanced. The correlation is a healthy .48, and the variance explained (r-squared) is .23. This means that a quarter of the variation we see in offensive production across leagues can be explained by the level of imbalance in a league. And in case you're curious which leagues are represented by the circles in the graph, below is the same picture, but this time with league names instead of circles.
Lest you think this connection between league balance and scoring is an artifact of using data from lots of seasons, think again. Below is the same graph, but this time only for the last 5 seasons of play. Guess what? The relationship is nearly identical - if anything, it's stronger as the correlation coefficient (.51) suggests.
The trend line is also helpful for identifying outliers. Clearly, the Eredivisie goal numbers are above the line, while Ligue 1 consistently falls below the line. This means that scoring in the Netherlands is higher and Ligue 1's goal lines are lower than league imbalance alone would lead us to predict.
What do we make of this? For one, it suggests that scoring is higher in more imbalanced leagues. Practically speaking, this may make Dutch-based strikers seem more appealing to English managers and perhaps more expensive than they should be, Luis Suarez's obvious (and unusual) quality notwithstanding. Looking at the graphs, it also may suggest that Ligue 1 offenses are less capable than they ought to be, given the league's level of imbalance. So maybe very capable French strikers are undervalued because they seem to score less, relatively speaking, though some of that is simply due to the level of parity in the league.
I suspect these data also might hold clues to valuing defenders and goalkeepers. The fact that scoring is higher in the Eredivisie at first glance might suggest that "Dutch defenders are rubbish", as a friend told me recently. But think again: perhaps Dutch defenses concede more because the league as a whole is imbalanced, not because individual players are any worse than their counterparts elsewhere. So here's an opportunity for a look at undervalued Dutch defensive talent.
Just a few hunches - and a bit of a leap, given the modest evidence presented here. And still ...
