Evaluating Competitiveness in UEFA's New Champions League Format
Karel Devriesere, Dries Goossens, Frits Spieksma
TL;DR
This study evaluates UEFA's shift from a group-stage format to an incomplete round-robin (iRR) Champions League design by precisely classifying match states as competitive, asymmetric, stakeless, or collusive and comparing formats via large-scale Monte Carlo simulations. The methodology combines integer-programming-based state identification, IP-driven draws and scheduling, and a Poisson/Elo-based outcome model to simulate 10,000 runs per configuration across six seasons, with appropriate tie-breaking rules. Results show that the iRR format substantially reduces stakeless and asymmetric matches and increases competitive ones, though it marginally raises collusion opportunities; scheduling strategies that balance matches across rounds further improve competitiveness and can align with TV objectives. The findings support UEFA's claim that the new format enhances competition, while also highlighting trade-offs between collusion risk and broadcast considerations, and offering concrete scheduling guidelines (e.g., balanced, late-round fixtures) to optimize outcomes.
Abstract
Recently, UEFA changed the group stage of its international soccer competitions to an incomplete round robin tournament. Previously, teams were divided into groups, each playing a double round robin tournament with a resulting ranking table. In contrast, the new format has all teams competing in one league, producing a single ranking. We investigate the effect of the new format on the number of competitive matches in the UEFA Champions League. A match is non-competitive if the prize for at least one opponent does not depend on the match outcome, or if there exists an opportunity for both opponents to collude; otherwise, we call a match competitive. Using Monte Carlo simulations, we show that the new format results in more competitive matches than the old format.