It's never who you think. College coaches become entrenched with huge guaranteed (even if you go to prison) contracts and benefits beyond your imagination with the power to control your athletic department. Those coaches are royalty and it's darn near impossible to fire them. Look how many years it took LSU to fire Les Miles.. literally like 5 years and he will stay in college for the same reasons as above. 

 

Then you have your Urban Meyers, Pete Carrols and Chip Kelly's who get out of dodge right before scandals come out . Ironically Kelly and Carroll are two of the three Head Coaches who's last job was on the collegiate level (Bill O'Brien who went from NE, to PSU and came back). My point here is that A) It's difficult to pull the good ones and B) The success level for guys with NFL experience is more valuable

 

Side note: Jeff Fisher would make a great college coach, he'd be one of the best recruiters like Saban, win 10 games a year with his garbage offenses and would find system QB's and could sit on his bum for 15 years.

---