The Red Sox has a great scout, why arranged tryouts for any number of great black players, and the Red Sox nixed them.
In 1945, the Red Sox tried out Jackie Robinson, who went on to become a six time All Star and MVP, and two other quality black players. Red Sox said no, and he played a decade for the Dodgers.
The Red Sox had a chance to sign Willie Mays in 1950, a year before he was a Rookie of the year for the New York Giants. He was a two time NL MVP, and a 24-time (not a typo) All Star.
The Red Sox were the last team to have a black player in 1959.
I am no baseball expert, but I am guessing they would have been a much better team if they had exceptional players like Jackie Robinson and Willie Mays.