Dealing with randomness in match outcomes: how to rethink performance evaluation and decision-making in European club football

In European club football, decision-makers often rely on recent match outcomes when evaluating team performance, even though short-term results are heavily influenced by randomness. This can lead to systematic misjudgments and flawed decisions when the random component is sufficiently large. We show that expected goals based on quantified scoring chances provide an evaluation metric that predicts future performance more accurately than do recent match results. Building upon this metric, we develop a chart that compares teams’ official league ranking to their ranking based on expected goals, which can alert decision makers to sensitive situations where a team’s true quality on the pitch is likely to deviate from the performance indicated by match outcomes due to random forces. Thus, incorporating this additional information into decision-making should enable clubs to avoid making poor decisions in certain situations and to improve the overall decision quality in the long run.