  This article shows how coworker performance affects individual performance
evaluation in a teamwork setting at the workplace. We use high-quality data on
football matches to measure an important component of individual performance,
shooting performance, isolated from collaborative effects. Employing causal
machine learning methods, we address the assortative matching of workers and
estimate both average and heterogeneous effects. There is substantial evidence
for spillover effects in performance evaluations. Coworker shooting
performance, meaningfully impacts both, manager decisions and third-party
expert evaluations of individual performance. Our results underscore the
significant role coworkers play in shaping career advancements and highlight a
complementary channel, to productivity gains and learning effects, how
coworkers impact career advancement. We characterize the groups of workers that
are most and least affected by spillover effects and show that spillover
effects are reference point dependent. While positive deviations from a
reference point create positive spillover effects, negative deviations are not
harmful for coworkers.
