Joe Cronin built an impressive resumé as a player, just as his predecessor Eddie Collins had. Also like Collins, Cronin gained enshrinement in the National Baseball Hall of Fame for his exploits on the field (Cronin entered Cooperstown in 1956). They also both possessed previous managerial experience before assuming front office roles with the Red Sox; Collins had been a player/manager for a little more than two seasons with the White Sox during the 1920s and Cronin served as a player/manager for 13 of his 20 seasons as a player, including 11 years with the Red Sox after joining the club in 1935. After the 1945 season, Cronin stopped playing the field but he led the Red Sox to the 1946 World Series as their manager.
When Collins became ill in late 1946, Cronin took on the additional duties of general manager before he was officially named GM at the very end of the 1947 season. Cronin hired Joe McCarthy to take over for him as the field manger and both the 1948 and 1949 Red Sox teams fought to the final day of the season before they were eliminated at the very last minute. The powerful Red Sox teams from 1946 to 1950 were largely built during Collins' tenure as GM but Cronin's importance as manager from 1935 through 1947 should not be understated.
Unfortunately, the Red Sox experienced a period of some decline through the 1950s and were more or less a middle-of-the-pack team during the decade. In January 1959, the highly-regarded Cronin was named the president of the American League and resigned his position with the Red Sox.