Using science to identify true soccer stars

Jun 16, 2010
Visualization of the three knockout-phase matches of the Spanish team.

(PhysOrg.com) -- As a young boy growing up in Portugal, Luis Amaral loved playing, watching and talking soccer. Amaral and his friends passionately debated about which players were "the best." But, it was just a matter of opinion. Unlike baseball and basketball, there isn't a lot of statistical information detailing how each soccer player contributes to a match.

Amaral, now a professor at Northwestern University, combined his love of soccer with his research team's computational skills to measure and rank the success of based on an objective measure of performance instead of opinion. The results of the study will be published June 16, 2010 , a journal published by the Public Library of Science.

Though their analysis, Amaral and his team were able to objectively rank the performances of all the players in the 2008 European Cup tournament. Their results closely matched the general consensus of sports reporters who covered the matches as well as the team of experts, coaches and managers that subjectively chose players for the "best of" tournament teams.

"In soccer there are relatively few big things that can be counted," said Amaral, professor of chemical and biological engineering with the McCormick School of Engineering and Applied Science and senior author of the paper. "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, eleven 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, co-author and Northwestern graduate student Josh Waitzman first wrote software to pull play-by-play from the 2008 Euro Cup website. This type of extensive statistical information is usually only gathered for important matches, Amaral said. Amaral and Jordi Duch, the paper's first author and an assistant professor of applied math and computer science at Universitat Rovira I Virgili in Spain, 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."

Amaral's team mapped out the flow of the soccer ball between players in the network as well as shooting information and analyzed the results.

"We looked at the way in which the ball can travel and finish on a shot," said Amaral, who also is a member of the Northwestern Institute on Complex Systems (NICO) and an Early Career Scientist with the Howard Hughes Medical Institute. "The more ways a team has for a ball to travel and finish on a shot, the better that team is. And, the more times the ball goes through a given player to finish in a shot, the better that player performed."

"It would never happen by chance that we would get such striking agreement with the consensus opinion of so many experts if our measure wasn't good," Amaral said.

He says this kind of analysis can be used outside of the world, too. Companies could use the method to rank and evaluate the performance of employees working together on a team project, for example.

Explore further: Hyperbolic homogeneous polynomials, oh my!

More information: The title of the paper is "Quantifying the Performance of Individual Players in a Team Activity." www.plosone.org/article/info%3Adoi%2F10.1371%2Fjournal.pone.0010937

Related Stories

New technique developed to evaluate basketball players

Jun 05, 2009

A team of Spanish and American researchers has developed a method to evaluate basketball players that will, they say, better meet the requirements of the sport's trainers and experts. The technique uses mathematical models ...

Soccer robots compete for the title

Apr 01, 2008

Robot soccer is an ambitious high-tech competition for universities, research institutes and industry. Several major tournaments are planned for 2008, the biggest of which is the 'RoboCup German Open.' From ...

Professor predicts Brazil will win World Cup

Jun 09, 2010

(PhysOrg.com) -- Government professor Christopher Anderson, a former semi-pro soccer player, has launched a statistically based soccer blog. He predicts Brazil will take the cup in South Africa this summer.

Recommended for you

Not just the poor live hand-to-mouth

6 hours ago

When the economy hits the skids, government stimulus checks to the poor sometimes follow. Stimulus programs—such as those in 2001, 2008 and 2009—are designed to boost the economy quickly by getting cash ...

Math modeling handbook now available

9 hours ago

Math comes in handy for answering questions about a variety of topics, from calculating the cost-effectiveness of fuel sources and determining the best regions to build high-speed rail to predicting the spread ...

Archaeologists, tribe clash over Native remains

9 hours ago

Archaeologists and Native Americans are clashing over Indian remains and artifacts that were excavated during a construction project in the San Francisco Bay Area, but then reburied at an undisclosed location.

Male-biased tweeting

11 hours ago

Today women take an active part in public life. Without a doubt, they also converse with other women. In fact, they even talk to each other about other things besides men. As banal as it sounds, this is far ...

Developing nations ride a motorcycle boom

13 hours ago

Asia's rapidly developing economies should prepare for a full-throttle increase in motorcycle numbers as average incomes increase, a new study from The Australian National University has found.

User comments : 1

Adjust slider to filter visible comments by rank

Display comments: newest first

jlarocco
not rated yet Jun 16, 2010
It seems the results could still be influenced by opinion.

If player A has control of the ball and wants to pass to B or C, all things being equal, wouldn't he pass to the better player?

If everybody thinks player B is the best player on the team, wouldn't part of the team's strategy be to utilize player B as much as possible?

More news stories

Male-biased tweeting

Today women take an active part in public life. Without a doubt, they also converse with other women. In fact, they even talk to each other about other things besides men. As banal as it sounds, this is far ...

Not just the poor live hand-to-mouth

When the economy hits the skids, government stimulus checks to the poor sometimes follow. Stimulus programs—such as those in 2001, 2008 and 2009—are designed to boost the economy quickly by getting cash ...

Archaeologists, tribe clash over Native remains

Archaeologists and Native Americans are clashing over Indian remains and artifacts that were excavated during a construction project in the San Francisco Bay Area, but then reburied at an undisclosed location.