Very true. There is less tolerance for middling black people in general, I jokingly refer to it as the Obama effect. Mediocrity in black people is often viewed as a function of their race rather than as the quality of an individual with flaws. If you aren't living up to the Obama standard you're sometimes thought to be a net negative compared to what might have been if there was a white person in your place. Mediocre white people are just assumed to be the best available option for the organization at the time. I've heard coworkers literally refer to other black people as "the price of diversity" (and just to be clear, their point was that the price was "worth it" in the name of diveristy). It sucks.