He is also remembered as one of the most successful and "probably the most famous 'old' player in history." Although, due largely to his military service, Wilhelm did not debut in the major leagues until he was already 29 years old, he nonetheless managed to appear in 21 major league seasons. He earned the nickname "Old Folks" while he still had more than a decade left in his playing career. He was the oldest player in Major League Baseball for each of his final seven seasons.