Skill, Strategy, and Passion: an Empirical Analysis of Soccer

Sports provide a natural experiment on individual choices in games with high stakes. We study soccer with a game-theoretic model of a match, and then evaluate the ability of this model to explain actual behavior with data from 2885 matches among professional teams. In our model, the strategy of a team depends on the current state of the game. When the game is tied, both teams attack. A losing team always attacks, while its winning opponent attacks early in the game, but it starts defending as the end of the match nears. We find that teams' skills, current score, and home field advantage are significant explanatory variables of the probability of scoring. We also find that a team which falls behind is relatively more likely to score. A team which is ahead, on the other hand, uses a conservative strategy very early in the match. These results support the main conclusions of our model. They indicate that soccer teams behave consistently with rationality and equilibrium. However, there is significant evidence that emotional factors are roughly as important as rational ones in determining the game's outcome, and they affect the strategic decisions of teams.