Evolution of Performance Indicators in Soccer during the Last Decade

Due to the worldwide negative impact on sport of the COVID-19 pandemic declared by the WHO in 2020, the first aim of this study was to analyze the influence of COVID-19 on performance indicators as a natural experiment, according to the moment in time: pre-COVID, COVID and post-COVID. The second aim was to analyze and ascertain the persistence of the performance indicators (PIs) over the analyzed seasons. To this end, 5320 teams’ match data corresponding to the 2014/2015 to 2020/2021 seasons of the LaLiga (first division of Spanish men’s soccer) were analyzed. All the seasons developed normally except the 2019/2020 season in which there was a three-month hiatus because of the COVID-19 pandemic, representing a natural experiment without spectators. Statistical tests including ANOVA, general multivariate linear analysis with three independent variables (covidtime, venue and result) and an autocorrelation were performed. The results obtained showed that there were significant differences in the PIs regarding the moment in time, the result, the venue, and the pairwise interactions among them. The evolution of the PIs has changed over the years, showing a decrease in the means of most of them, leading to a more passive game with tighter results; differences which could be generated by the change in the rules (from 3 to 5 substitutions), the total or partial absence of spectators, three months of confinement and inactivity, or the accumulation of matches and minutes played by the individual players. The teams’ technical staffs should bear all of these types of situations in mind as the seasons evolve to adapt as quickly as possible to a more effective game style in order to achieve objectives.