During a minor league game on July 7, 1953, Zimmer was struck in the head by a pitch thrown by pitcher Jim Kirk, and lost consciousness. He suffered blood clots on his brain that required two operations. He woke up two weeks later, thinking that it was the day after the game where the incident took place. This eventually led to Major League Baseball adopting batting helmets as a safety measure to be used by players when at-bat. Phil Rizzuto was the first player to use a batting helmet.