What does it depend on for a soccer player to score a goal? In addition to your own abilities, there are other external factors such as the position in which you play or the team to which you belong that determine this fact. Because of that,players with better scoring qualities may end up scoring fewer goalsthan others with lower performance, and vice versa. With this idea in mind, a team of researchers from the universities of Granada and Jaén has developed a model based on Bayesian statistics that allows predicting the goals that a soccer player will score based on their individual qualities.
Analyzing the performance of soccer players in the Spanish league, from 2000/2001 to 2008/2009, scientists have come to the conclusion that, globally,the best scorer was Rivaldo, followed by Robert, Ezequiel Garay, Luis Cembranos and Roberto Carlos. Analyzing according to the position of the player, the best midfielders were Rivaldo, Robert, Luis Cembranos, Mark González and Mostovoi; among the forwards stood out,Messi, Ronaldo Nazrio, Makkay, Villa and Etoo; and the most capable defenders were Ezequiel Garay, Roberto Carlos, Campano, Cristian Álvarez and Larrazábal.
“It is striking that the forwards appear in global positions that are not very high,” explains José María Pérez Sánchez, one of the authors. “In fact, apart from Messi, who is in the sixth position, the rest appear below the 15th position.” This is because the model is more demanding with the forwards in relation to the expected number of goals, and rewards defenders and midfielders for scoring, since this is not their main mission in the game.
By eliminating external factors such as the number of minutes played, the quality of the team and the position on the playing field, the model makes it possible to assess the performance of a player, in terms of goals, and compare the number of goals scored with the one that would be expected to score a footballer who played the same time, in the same position and in the same team.
Taking into account data from several seasons, the study, which is published in the journalEuropean Journal of Sport Science, has made it possible to analyze the individual trajectory of several emblematic players in the Spanish league such as Leo Messi, who “in the 2007/2008 season experienced a sharp decrease in their productivity”, explains the researcher. Most likely this decline is due to the change in position in the field, from midfielder to forward, so the statistical model would require a higher performance.
