Pitchers by Race, MLB 1947-2018

Source: https://sabr.org/bioproj/topic/baseball-demographics-1947-2016/

Unlike with the outfield, pitching in the Major Leagues remained a relatively homogenous role with Black pitchers never making up more than 10% of all MLB pitchers.  Latino pitchers have seen a bit more success in breaking through to the Majors, but three quarters of all MLB pitchers are White to this day.