The UEFA Champions League seeding is not strategy-proof since the 2015/16 season

TL;DR

This paper demonstrates that the UEFA Champions League seeding process has not been strategy-proof since 2015/16, allowing incentives for teams to manipulate outcomes, and suggests policy changes to improve fairness.

Contribution

The paper identifies incentive incompatibilities in UEFA's seeding rules since 2015/16 and proposes policy adjustments to ensure fairness and strategy-proofness.

Findings

Seeding rules violate incentive compatibility since 2015/16

High-ranked league champions can harm top domestic clubs

Policy recommendation for fairer seeding from 2021-24 cycle

Abstract

Fairness has several interpretations in sports, one of them being that the rules should guarantee incentive compatibility, namely, a team cannot be worse off due to better results in any feasible scenario. The current seeding regime of the most prestigious annual European club football tournament, the UEFA (Union of European Football Associations) Champions League, is shown to violate this requirement since the 2015/16 season. In particular, if the titleholder qualifies for the first pot by being a champion in a high-ranked league, its slot is given to a team from a lower-ranked association, which can harm a top club from the domestic championship of the titleholder. However, filling all vacancies through the national leagues excludes the presence of perverse incentives. UEFA is encouraged to introduce this policy from the 2021-24 cycle onwards.