Northwestern University Professor Luis Amaral said that unlike baseball and basketball, there isn't a lot of statistical information detailing how each soccer player contributes to a match. But he says he and his research team have created a technology that can objectively rank the performances of soccer players.
"In soccer there are relatively few big things that can be counted," said Amaral, a professor of chemical and biological engineering. "You can count how many goals someone scores, but if a player scores two goals in a match, that's amazing. You can really only divide two or three goals or two or three assists among, potentially, 11 players. Most of the players will have nothing to quantify their performance at the end of the match."
To find a quantitative way to rank players, Amaral and co-author Josh Waitzman, a graduate student, said they first wrote software to pull play-by-play statistical information from the 2008 Euro Cup Web site. Then Amaral and Assistant Professor Jordi Duch of Spain's Universitat Rovira I Virgili used the data to quantify the performance of players by generalizing methods from social network analysis.
"You can define a network in which the elements of the network are your players," Amaral said. "Then you have connections between the players if they make passes from one to another. Also, because their goal is to score, you can include another element in this network, which is the goal."
The research is detailed in the online journal PLoS One.