Performance models in the English and Italian professional soccer championships

Scored and conceded goals are important performance indices in an international cup or national professional soccer league (Lanham, 2005). These parameters concur with many others to determine the outcome of the championship (Hughes, 2004). The aim of this study is to investigate the relationships between selected match parameters in the English and Italian professional soccer leagues and to compare the two performance models. Methods All the games of all the teams participating to the English Premier League and the Italian Serie A in the 2006-2007 season were considered for the analysis. The following data were collected: points; home and away scores, wins, draws, losses; scored and conceded goals in the four quarters of the match; positional role of the goalscorer; substitutions in the different quarters of the game; bookings and expulsions. For each team, peaks and minimums of scored and conceded goals during the season were estimated with 5th order moving averages, and compared with the team’s seasonal mean values. Sixth order polynomial curves were used to asses the positive phases for the attack and the defense, characterized respectively by a higher scored goals trend and a lower conceded goals trend compared to the seasonal mean values. The number of positive rounds, and positive and negative periods, were considered as performance indices during the competitive season. Hierarchical cluster analyses (performed with the SPSS package) were used to classify the performance indices and the teams in the two championships. Results In the analysis of single matches three clusters are shown in the English Premier League. The first one may be defined the “success” cluster including, with decreasing importance, points, home wins, goals scored between 45’ and 68’, away wins, midfielders’ goals, goal scored in the first and the last quarter of the game, the forwards’ goals, substitutions in the last quarter. In the “failure” cluster are included, in the following order: home losses, conceded goals, away losses, substitutions in the first half of the game, bookings and expulsions. Home and away draws are surprisingly linked to defenders’ goals in the third cluster. The Italian Serie A model shows only two clusters, since away draws weakly link with the success cluster, while home draws with the failure. The second cluster analysis, performed on time series of the entire season, shows similar clusters between the two leagues, however with an important difference. In fact, the success in the Premier League is connected with the mean of scored goals and the sum of positive rounds of the attack, while in the analogous cluster the Italian Serie A shows the sum of positive rounds for the defense. Discussion The success in the Premier League appears especially associated with the attack’s performance, while in the Italian Serie A the defense’s performance seems more determinant. The cluster analysis carried out on each team enables detection of the correspondence of the team behaviour vs. the model performance of the entire league. Thus, typical and atypical clubs may be characterized. The single match performance indices may be useful to the coach from a technical and tactical perspective, while time series analyses performed on the entire season may suggest valid information for the physical training programme, differentiating between the positional roles.