When UEFA rules had inspired unfair behavior on the field (1806.03978v5)

Abstract: One of the most serious violations of fairness in sports is when a team has clear incentives to lose a match, which hurt a third, innocent team. This is shown to be not only a theoretical possibility as the recently identified incentive incompatibility of the qualification for UEFA club tournaments created such a situation. In particular, we present that SC Heerenveen was ex-ante interested in losing compared to playing a draw on its last match in the 2011/12 Eredivisie, the highest echelon of professional soccer in the Netherlands. In the absence of perverse incentives, the team would probably make more efforts to kick a goal, and a successful attack would send PSV Eindhoven to the more prestigious UEFA Champions League instead of the UEFA Europa League. Our example may inspire the governing bodies of major sports to consult more with the scientific community, especially before rule changes are implemented.