As Coach Bryant told us, Florida is a gold mine/sleeping giant. The last four Florida coaches:
Steve Spurrier (previous HC at Duke)
Ron Zook (previous coordinator)
Urban Meyer (previous HC at Utah)
Will Muschamp (previous coordinator)
So..all that to say this...you have to be VERY special to make the jump from coordinator or position coach to HC at a big time program and be successful right away or an AD and fan base that will be very patient with you. Jimbo Fisher is a special case because he was basically the HC during Coach Bowden's last few years, but in the football sense only. Coach Bowden still shouldered all the rest of the burdens. So that eased him into it.
But look around the SEC. Gus eased into the door at Arkansas, went to Tulsa, then came to AU as an OC. He went to Arky St. to cut his teeth as a HC and then came to AU as a HC. Hugh Freeze cut his teeth as a HC at Arky St. also. Les Miles coached at Okie St. when they weren't necessarily a power house program and got his feet wet there before coming in to maintain and enhance the groundwork that Nick Saban laid in Baton Rouge. And speaking of Coach Saban, his nomadic behavior is well-documented. But his first head coaching job was at Toledo. Most of the guys who have big time success have paid their dues, and not jumped directly from coordinator to head coach. Dan Mullen falls into that second category. He has an AD and fan base that have been VERY patient with him and his development of their program and they are now reaping the benefits.
I think Jeremy Foley goes hard after Mullen (although I heard the two don't quite get along), but I don't think Mullen leaves Miss. St. What's going on there right now is his baby. That's all of his sweat and hard work that's manifested itself as a #1 ranking in the country no matter how short lived it'll be. But whoever Florida gets, it'll be someone who has already been a head coach.