Who’s afraid of the GOATs? - Shadow effects of tennis superstars

In multi-stage tournaments, anticipated competition in future stages might affect the outcome of competition in the current stage. In particular, the presence of superstars might demotivate the next-best competitors from seeking to advance to later rounds, where they ultimately are likely to face a superstar. Data from men’s professional tennis tournaments held between 2004 and 2019 affirm that the participation of superstars (Djokovic, Nadal, Federer, and Murray) reduces the probability that the remaining Top 20 players win their matches. Such shadow effects arise even in very early tournament stages, in which favoured players lose more often than expected, given their ability. The effects are more pronounced when multiple superstars compete in the tournament and disappear once all superstars have been eliminated from competition. Furthermore, shadow effects increase the probability of retirement of strong but non-superstar competitors and disappear once superstar performance is not dominant.