Score contribution per author:
α: calibrated so average coauthorship-adjusted count equals average raw count
This study aims to contribute to the recent literature on the effects of COVID on football teams’ performance, focusing on the impact of ghost games on offensive and defensive technical efficiency. Using season-level data for the top 5 European leagues, a novelty for efficiency studies on football, the analysis compares the ten seasons played before the pandemic outbreak with the only season (2020–21) almost entirely played behind closed doors. A further novel contribution is the methodology – conditional order-m – applied to calculate efficiency scores. Our results show that in the post-COVID season both offensive and defensive efficiency significantly increased for away games, whereas for home games offensive efficiency shows a very slight increase, and defensive efficiency remains basically unchanged. These findings are valid for all the five leagues and provide evidence of a generalized reduction in the home advantage.