Absolutely. And if only 1% of your staff is black you've got to suspect that something else is already in play...
Starting with "how many African Americans have an education in tech?".
When I went to university, I do not remember a single black person in my courses. Since then, I've known only a handful in tech.
I've known and worked with Chinese, Vietnamese, Korean, Indian, Sri Lankan, Nepalese, Czech, Russian, Australian, Egyptian, Pakistani, Turkish and pretty much every other nationality I can think of -- which makes for awesome company pot lucks.
And, for reasons I cannot even begin to explain, the only blacks/African Americans I've met have been what I'd call "recently African" (ie. first generation immigrants).
I have never known anybody who refused to hire a qualified black candidate. But, in my experience (which admittedly doesn't cover everything), there's simply not many applicants.
So, the question to ask is: do blacks, as a group, even go into tech? Are they self excluding from the profession? Is the education system failing to get them into it?
I don't think it's so much that people are excluding anybody, it's that you can only include people who come to the game.