Sports psychologists Increase confidence and, to a much smaller degree, team spirit.
Psychologist do not help protect you against overconfidence. This was explained in a Q&A on Global by HT-Tjecken: Q: So overconfidence can happen more often. To prevent it I should hire the maximum number of psychologist. Not fire them? A: Psychologists boost your confidence, they're not at all useful to lower it. So I should sack them in case of overconfidence and not hire more.