I have a hard time agreeing that black pitchers are "disadvantaged." Simply put, there aren't that many black pitchers in the major leagues. I can only think of a few off the top of my head:

Sabathia

Willis

Ray King

Tom Gordon

Darren Oliver

There might be like like 10 more, but even still (I wish I could actually find a number on how many black pitchers are in the Majors right now but I couldn't), that's a tiny sample size. One pitcher's poor control (Willis maybe) would have a HUGE effect...

That gives us way too small of a sample size to see if umpires are biased. I'd chalk the black/white difference up to a few black pitchers who don't have great control, especially once you notice that white pitchers got more called stirkes from all races of umpire. In addition, there are only a few non-white umps in the majors, which means that one umpire's tendencies could make a big difference in the study. I'd like to see it broken down ump-by-ump....

I just feel taht the stats taken on minority have way too small a sample size in terms of both players and umpires, which hurts the study in general. It's not unimaginable that umps are slightly biased in terms of race (by accident), but this study doesn't tell me much....