Complex sentence: Jolley is known to many only for his major league career; however, before and after his major league career, he had a long, successful career in the minor leagues, in an era when the minor leagues were independent teams.
Split into simpler sentences: Jolley is known to many only for his major league career. However, before and after his major league career, he had a long, successful career in the minor leagues, in an era when the minor leagues were independent teams.