Hire good people, don't deny them on the basis of their immutable qualities. Don't pick someone because they look a certain way, but because they can do the work.
I'm not joking.
I have tried multiple times to hire a friend, who is black, because he is good (and not because he's black), and have failed every time because his cultural support structure is simply not there. That's not his problem, and honestly, it's not the Valley's problem, it's just a factr.
It took me a long time to understand this, but I realized, there's lots of places I wouldn't move, either, even for a good opportunity, because my expectations about the culture is some places and not others.
There is a rate of migration now and then, but honestly, there is a serious geo problem. Some people go where the jobs are (born here, but grew up out east), some won't, and there's nothing wrong with that.