Joe Cronin hired Dick O'Connell shortly after World War II to serve as assistant general manager and when Cronin left to become the president of the American League in 1959, O'Connell was promoted to business manager of the ballclub. By all accounts O'Connell was a good administrator and during a 1961-62 stretch when the Red Sox had no formal general manager, O'Connell effectively functioned as such while carrying the formal title of Executive Vice President of Business and Baseball Operations. When Tom Yawkey cut ties to Pinky Higgins in September 1965, the owner bestowed the official GM title upon O'Connell.
The club O'Connell inherited finished only a half-game out of last place in 1966 but after the season, O'Connell named Dick Williams to be the new field manager. Along with Williams, the 1967 Red Sox also benefitted from the development of many of the players who O'Connell helped place in the team's farm system in the beginning of the decade. The 1967 "Impossible Dream" Red Sox won the American League pennant and took the World Series to a seventh game, reviving fan interest in the process. In addition, the 1967 roster was racially diverse and O'Connell is often credited with opening up the team's ranks to the point where merit reigned supreme above any other considerations.
With renewed fan support, the Red Sox stayed above .500 from 1967 to the end of O'Connell's tenure as GM. In 1972, the team came within a half-game of winning the division and in 1975 the Red Sox took the World Series to a seventh game for the second time in nine years. After Tom Yawkey passed away in 1976, jostling for control of the team ensued and O'Connell was eventually let go on October 24, 1977, after 31 years with the Red Sox.