Joz,
Your question is easy and I am sure you already know the answer. Tommy has his job after years of brutal performance the same way:
Denny Green (Previously at Minny)
Denny Green (Now at Arizona)
Llyod McClendon (Previously at Pgh Pirates)
Mike Davis (Previously at Indy)
Herm Edwards (Previously at NYJ)
I could go on. NO, I am by no means a racist. That said, the bottom line is evey one of these situations above went on for at least a year or two beyond what would have been tolerated by Management, The Owners, or The Boosters if the man in charge was not of a Diverse background. I am not by any means suggesting they did not deserve their jobs when hired, in the same light they all were afforded to stay on well beyond their effectiveness or lack there of. Denny Green and Llyod McClendon are CLASSIC examples. You could almost say the same for John Thompson and Don Cheney at the end of their tenures. After what Cheney did he should have been fired the next day but the Temple Administration were advised by their Legal Council to walk on egg-shells.
Just a few toughts.....