Earl Wilson had a decent first full season in the Majors in 1962, with a 3.90 ERA in 31 games and 28 starts. Also, since pitchers still had to bat in the American League for most of his career, Wilson added 3 home runs at the plate in 1962. Throughout his career, Wilson hit .195/.265/.369 with 35 home runs, not at all shabby for a pitcher.
In his first couple of seasons, Wilson was rather wild, walking 111 in 1962 and 105 in 1963. But his control vastly improved in 1964, which was actually one of his worst seasons in the Majors. From 1959 to 1966, Wilson was worth 8.2 WAR on the mound and 3.9 WAR at the plate, with a 4.10 ERA (95 ERA+) in 156 starts and 174 total appearances.
From these numbers, it would seem Earl Wilson was a solid but unexceptional pitcher for the Red Sox. That much is true. But, as with many decent players that the Red Sox had throughout the 20th century, they traded him away before he delivered on his promise.
In mid-1966, Wilson was traded to the Detroit Tigers for utility player Don Demeter. While Demeter was a decent player in parts of 1966 and 1967 for the Red Sox, Wilson was exceptional for the rest of 1966. He'd produce 12 WAR for the Tigers over 5 seasons with a 3.51 ERA in 145 starts (149 total appearances).
Wilson's career would end in 1970 with the San Diego Padres, but he ended his career with 27.6 WAR in 11 seasons. The Red Sox would've been happy to have him from late 1966 to 1969, missing out on 3 of his best seasons in the Major Leagues. Had that trade not happened, Wilson would’ve been part of the 1967 Impossible Dream team. Who knows what he may have brought to that team’s starting rotation?
It always seemed like the Red Sox were one or two pieces away from winning championships, and Earl Wilson could've been one, just like so many others the Red Sox gave up on too soon.