I think that AD Bubba Cuningham and the UNC big money came up with a plan that makes a little sense. They realized that if they went after the latest, hotest MAC coach or a seasoned veterrn (Jimbo), they woul still be just Carolina. That's a middling program that will win 7 +- games each year and occssionally generate some excitement. Hiring BB comes with risk but a much higher upside that any other coach can bring. He will create a pro-type atmosphere focused on getting players to the NFL and that may appeal to many athletes.
This corporate structure may be visionary and BB may be introducing the next seismic change to college football. If he is an utter failure, the shrt term of the contract minimizes risk. It'll be an interesting few years at Chapel Hill, that's for sure.