Complex sentence: Keefe entered the major leagues in 1880 with the Troy Trojans and rose to stardom in 1883 with the New York Metropolitans when he had one of the most dominating seasons in baseball's early history.
Split into simpler sentences: Keefe entered the major leagues in 1880 with the Troy Trojans. Keefe rose to stardom in 1883 with the New York Metropolitans when he had one of the most dominating seasons in baseball's early history.