Chizik was not available either. All five were currently employed somewhere. The point of the question is stated quite clearly within it. More importantly, it remains unanswered.
As for the 2010 BCS National Championship, three of those men have won more than one of them. Urban Meyer, for example, would have likely still sought Cam Newton if he were here instead of Florida. Maybe we win it with one of those four in 2010, maybe we don't. Maybe we win it in 2011 or 2012 with them.
Point is, all four of them have built and maintained teams that are consistently in the hunt for it. None of them left everyone scratching their head when they were hired. They were established winners (as head coaches) elsewhere. None of them left people with legitimate concerns about the state and future of their programs in the fourth year of their tenure. I have no selective memory. Credit Chizik for that magical season, I'm fine with that. Credit Chizik for the nose-dive into the abyss that we have subsequently taken, as well. He gets both, you don't get to exclude one. When the stars align perfectly with both coordinators and two ridiculous players, he can preside over something that can win it all. When they don't, it plummets like the Titanic. I can do without having both extremes, with just mediocrity between them.