I don't feel like you're the most intelligent individual, or at least you don't observe. While Saban certainly succeeds in the recruiting department, year in and year out what makes his teams elite is their execution on Saturday, an execution of their practice.
While I'll agree that college and professional football are different, to say that a person who is geared towards execution can't be successful is absurd. Surround that coach with a staff who are excellent recruiters and you have a recipe for success.
The problem with a Gruden, just like many LSU fans' fascination with Jack Del Rio, is that he is high risk. Both have a very high ceilings, but both also have very low floors.
We know they can coach, but will they realize how the limited practice times will constrain what they can accomplish; will it frustrate them. Yes they can hire great recruiters, but your head coach has to be the closer. The raw material is there to be great, but will they like and want to do it? What about relationships with boosters and high school coaches? Will there egos permit them to do what's required and necessary? With their limited and dated college experience, they probably don't have a clue themselves as to how they will react.
The point isn't that they can't or won't be very successful in college; it's that they could also do very bad and it could go either way. It's human nature to overstate the upside and underestimate the downside. It's a recipe for failure.