Blending speed and power, Harper became only the fifth member of the “30-30 Club,” hitting 31 HR and stealing 38 bases for the 1970 Brewers. As a young, highly touted outfielder with the Reds in 1965, he hit 18 homers and led the NL with 126 runs scored. After a disappointing 1967 season (.217), he was traded to Cleveland, where he continued to slump in a platoon role. Rescued by the Seattle Pilots in the 1968 expansion draft, he led the ML with 73 stolen bases in 1969, the highest AL total since Ty Cobb‘s 96 in 1915.
Although he preferred the outfield, Harper played mostly at third base (and 82 games at second base) for the Pilots and Brewers. Traded to Boston before the 1972 season, he returned to the outfield. In 1973 he was the Red Sox’ MVP, hitting 17 HR, scoring 71 runs, and stealing an AL-high 54 bases.