I think the whole Petrino-gate thing is a big factor. That happened in 2003, the off-season before AU went undefeated. Yes, the President and/or AD got fired, but all the coaches in the world know that it was Lowder that was really behind Petrino-gate and not the scapegoat administration.
You may or may not agree on this (I said it on Nafoom the other day), but I really think there are maybe only 10 current coaches in the college game that I would say would be an upgrade from Tuberville. There are others that I would call maybe a push or a lateral move for Auburn, but only 10 or less that I would say would be an upgrade, and all of those coaches have jobs that they will not be leaving. So, in the end, I just don't see how Auburn will be able to upgrade. Maybe they'll be able to find an up and comer that's the next Bob Stoops, but I definitely don't think they'll be able to make a hire that would look like an upgrade immediately.