For a decade, Petrocelli was a home-run threat with the Red Sox infield. He was with Boston for their 1967 and 1975 pennants, maturing from a volatile young player to become a steadying influence on his teammates. In Game Six of the 1967 World Series, Petrocelli, Carl Yastrzemski, and Reggie Smith set a WS record by hitting three HR in an inning (the fourth). It was Petrocelli’s second shot to clear Fenway’s Green Monster that game. His rare combination of power and infield glove work was displayed best in 1969, when he set an AL record for most home runs by a shortstop, with 40, and tied a then-record for fewest errors by a shortstop, with 14.
Petrocelli was moved to third base in 1971 after Boston acquired Luis Aparicio, and led the league in fielding his first year at his new position. But elbow problems in 1974, and a leg injury and beaning in 1975, cost him playing time. He hit just seven HR in ’75, but batted .308 in the WS. Inner-ear problems helped to end his career.