A good recruiting college coach isn't necessarily a good NFL coach. The NFL's even distribution of talent has put more than one ex college coach in a hurry to return to college.
Urban Meyer is like a woman going through menopause and can't find her hormone meds. I speak from experience and you do not want that person coaching your football team or within reaching distance of sharp objects.
And I am not bashing the man, he has some struggles and wasn't on any team's short list after openly campaigning for the Cowboys job.
I don't any of us can know the real difference between coaching a bunch of 18-23 year old's, and having 80 of them and dressing 60, and being able to be the disciplinarian for them to keep them in line and having 23+ paid players and only dressing 45 of them and having few of those punching bag teams because the 4 and 5 star recruits are disproportionately distributed. There is a good reason why Bama, Clemson, Georgia, OSU and OU are always vying for the CFP.
Saban and Spurrier couldn't wait to get back and Kelly had assistance in getting back but the vision that sticks with me was Bobby Petrino on the Falcons sideline in a MNF game after all of that vick crap went down and the look on his face when some of his players pulled up their jerseys showing t's protesting vick even being disciplined. He was in shock and embarrassed and the next week he was calling the Hogs.
Meyer is a risky hire for any college or pro team and if you want Riley, you'd better find the best DC money can buy. I think Matt Rhule is the exception but he was already in the NFL and knows the terrain. He was also smart and got a contract that pretty much gives him job security longer than most NFL HC's. Not that his owner wouldn't buy him a ticket on the 3"10 to Yuma, he's the fattest cat in the league.