Players can get the yips
The word yips is originally a golf term that meant “a brain spasm that impairs the short game.” In MLB, it’s used to describe when a player can no longer do some routine thing, like throwing to first. It used to be called Steve Blass Disease, for the pitcher who could no longer throw strikes. Second basemen Steve Sax and Chuck Knoblauch each had it, where they could no longer throw to first without the ball going awry.
Sax conquered his issue, but Knoblauch never really did. He even accidentally hit Keith Olbermann’s mother in the stands, then got switched to the outfield, and then was out of baseball. There appears to be a psychological component, and it could be neurological, too.
Some cases are more debilitating than others. Jon Lester has the yips when it comes to throwing to first base, but it really hasn’t derailed his career.
Even talking about it is a huge taboo in baseball. Dodgers pitcher Brandon McCarthy experienced the yips after coming back from Tommy John surgery in 2016. He was one of the rare players to talk in public about this after he got over it. Orel Hershiser, the team’s pitching coach, gave McCarthy credit for his candor, and said that he still has never discussed with old teammate Sax when that player had the yips.