Caroll did 15 years in the NFL as an assistant before USC. Harbaugh had a long career as a player in the league. Saban was worthless in the pros.
To me College coaching is about recruiting - not scheme. How complicated is an offense when the QB looks at the sideline before a snap and someone is holding up a picture of a squirrel or whatever. They probably have a handful of play, blocking, and route concepts. That won't fly in the NFL.
When you look at Saban's Alabama career - what percentage of games did they play where the other team had more talent than them? 5% - maybe? In the NFL - you have to coach on a level playing field or sometimes when you're overmatched. That's my biggest problem with major college football - too many full ride scholarships allow the recruiting rich to get richer and so many of the games are won before kickoff.
