 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 , he did not debut in the major leagues until he was already 29 years old , Wilhelm nonetheless managed to appear in 21 major league seasons . He earned the nickname " Old <unk> " 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 . 
