Two reasons the Urb had health problems and ultimately left Florida are:

1.  The culture was broken.  Urb hasn't elaborated on this but, IMO, players felt entitled, smoked pot, treated women poorly and didn't pull for one another.  A small part of this was because Urb didn't go to the celebration dinners, and was fixated on recruiting at the expense of his current players.

Urb seems to have genuinely bonded with each of his teams.  He seems to be more present.  The drug testing that happened with this years team at the end of October seems to show a tougher stance on drugs.

2. He didn't do as well replacing assistants.  Some of these guys had been with him since the beginning and they knew what he wanted.  He didn't have to communicate as often to them, and they were talented. 

I think Urban has grown is his ability to lead coaches and effectively communicate his vision to them since his time in Florida.  I also think there are more top level coaches that call the state of Ohio "home" than at Florida.  His recruiting pitch at Florida was good but all of the guys (except Withers) on his first staff had ties to the great state.  The first two steals from ND both came to a rebuilding project on a lateral move because they are Ohio born.

Urban has an easier time getting the best assistants at Ohio State because Ohio State has a great GA program, amazing coaching trees from Woody, Bruce, even Cooper, and Tress, great HS coaches, and some High level college programs within the borders, like YSU, Mount Union, and Cincinnati, that have had good to great coaches in the last 20 years.