This is my first joint entry on my race and my baseball stats blogs!
Was looking at the cumulative stats for times hit by pitch (HBP) in the early years of black players in the historically white major leagues. (BTW, kudos to Major League Baseball for fully recognizing the "Negro Leagues" as "major leagues," and to baseball-reference.com for fully integrating the Negro League stats (such as they are) into their database.)
Using fangraphs.com, I looked at the stats from 1947-56 cumulative (1947 being, of course, the year the color line in major league baseball was crossed). Here's what I came up with for highest rates of being hit by pitch per Plate Appearances (PAs), minimum 1000 PAs for the range of years:
119 4598 38.64 M. Minoso Black (Cuban)
032 1345 42.03 Fr. Robinson Black
080 3874 48.43 Sh. Lollar white
053 2823 53.26 Sol Hemus white
021 1246 59.33 T. Glaviano white
028 1931 68.96 Luke Easter Black
033 2352 71.27 F. Hatfield white
080 5745 71.81 Nellie Fox white
037 2712 73.30 Al Smith Black
028 2167 77.39 C. Courtney white
025 1975 79.00 Sam Jethroe Black
072 5802 80.58 J. Robinson Black
To clarify, this chart indicates that Minnie Minoso, for every 38 and 2/3s times he would step to the plate through 1955, it would end with him would be awarded first base due to being hit by a pitch.
So, we see that six of the 12 players most likely to be hit by a pitch during these 10 years were Black. This may not seem that stark a number, until we realize that of the 300 players who "qualified" based on at least 1000 PAs during those 10 years, only 19 of them were Black (or Latin Americans whose dark skin would have kept them out of the historically white leagues pre-1947). Thus, black players constitute only 6.3% of the player pool, but 50% of the HBP leaders for those years.
This provides empirical evidence for the many accounts from early black players of being targeted by pitchers for their skin color. There is an alternative explanation--some players (Ron Hunt in the 1970s being the most notorious) are known to SEEK being hit by a pitch, crowding the plate and leaning into some pitches, as a way of getting on base. On the list above, for instance, it may be that Minoso, Frank Robinson and Nellie Fox were known for, if not seeking, at least not minding reaching base in this way. But, far more likely, it is a case of white pitchers, often with the support and encouragement of management and teammates, sought to intimidate de-segregation pioneers, perhaps even with the hope of reversing the change. For, much like school integration in the decade plus following the Brown decision, baseball integration was more a trickle than a flood early on. According to https://en.wikipedia.org/wiki/List_of_first_black_Major_League_Baseball_players, only twelve black players had appeared, on only five of the 16 historically white teams through 1950, four years after Jackie Robinson broke the barrier. It wasn't until 1954 that over half of the teams had "given in" to the new reality, and 1959 until the last team (the Boston Red Sox) was integrated.