This is one of the important reasons why there is a Rooney Rule in the NFL. It states that any team hiring a new coach must include African Americans in the search. They must have interviews and a chance to win the job.
Otherwise, teams just select who they want, which inevitably is a former somebody who happens to be white. It's not that racism is at play. It's just a football decision.
Now, the fact is Mike Shanahan would be a great hire for the Washington Redskins, and there should be some type of exception for former coaches who have demonstrated success.
The most notorious instances where problems arise are when unproven or failed coaches are hired without given African Americans, often with great experience a legitimate chance.
So, the NFL has definitely made strides, but we must remain vigilant.
I agree with the Chris Rock joke, that you will know it is fair when horrible black coaches get good jobs in the NFL.
That would be like a ...
For white examples see...
btw. there are no female coaches.