Catching is a highly technical skill, unlike playing the outfield where sheer footspeed matters most. So, as African Americans have lost interest in baseball, the number of African Americans catchers has dropped particularly sharply. In Bill James' second version of his Baseball Historical Abstract covering 1875-2000, there are only four African American catchers among the top 100 catchers, and those from fairly early after integration (Roy Campanella, who had an Italian father, Elston Howard, John Roseboro, and Earl Battey). In contrast there are 27 African American centerfielders (the position demanding the most speed) among the top 100.
So, it's not surprising that a star catcher with some black descent will have grown up in a largely white cultural milieu.