Here is a way to look at it. Gregg is smart, like way smarter than the average NFL player. Gregg is proud, confident, but not cocky or arrogant. In my opinion, he may just work out as a CEO type of coach. If you have someone who is not a control freak (Rhule) or set in their system/ways (Frank), your main goal is to identify hard working assistants who are experts in their field who will create a culture that is conducive for improvement without micromanaging. Gregg, knows culture from his playing experiences both good and bad. Gregg is the son of a coach, a very successful coach. He has been to a super bowl and he has also been on terrible teams.
Additionally, he has been watching the league and studying the players of nearly every other team on a daily basis. Olsen has likely made contacts that we are unaware of through attending practices, watching games, and doing interviews for the past 3 years. The division of labor with a NFL staff is SO DTEAILED. Some teams have coaches just for game management. McVay has a guy to make sure he doesn't walk too far on the field. Some HC's do not call any plays on either side of the ball. If he can create a level of buy in and surround himself with guys who he will let cook, he is much improved from many retreads or flavor of the month assistants.
Just a thought. Like G.O. said, "don't confuse experience with competence"... Right Frank/Rhule?