Five-year peak: 1965-69
WAR: 29.5 

Groat was traded to the Cardinals after 1962, and after spending parts of the next two seasons next to Dick Schofield, Mazeroski got his next great partner in the form of Gene Alley. Alley was never much of an offensive threat, but he was so highly thought of as a shortstop that he collected MVP votes in two separate seasons. Alley might never have become the shortstop he was without his veteran teammate; as recounted in Mazeroski’s biography, a then 20-year-old Alley, two years away from reaching the majors, watched his future partner take infield practice during spring training and realized that as good as he thought he was, he’d need to significantly improve his game to make it in the bigs. He did: In 1966, their second year together, they set a still-standing record by turning 161 double plays, and in 1967-68, became one of just eight middle infield pairs to each win multiple Gold Gloves together. They each retired following Pittsburgh’s 1972 World Series appearance, having never played for another team.