While with St. Paul in 1953, Zimmer nearly died after being hit in the temple with a pitch. He was not fully conscious for 13 days, during which holes were drilled in his skull to relieve the pressure of swelling. His vision was blurred, he could neither walk nor talk and his weight plunged from 170 to 124. He was told his career was finished at age 22; fortunately for Zimmer, the prognosis proved incorrect and he made it to the major leagues the following year.