Every historically elite program has had the same situation where they've had 3, maybe 4 truly great coaches in their history and the rest have either been dogs (often multiples in a row) or have been very good but never got to great, often because they just couldn't win the Big Game (John Cooper comes to mind as the poster boy). That they've had 3 or 4 is often why they got to elite in the first place. (Incidentally, there are a few programs who have really only had 1 truly great coach, and/or one or two who stayed for a very long time). If anyone can name a program with as many as 5, please do.
There are a lot of bad coaches and a lot of very good coaches, but there just plain aren't many truly great coaches out there, and there never has been.
And a truly great coach, assuming proper administrative support, can make almost any team great. A stark example is Bill Snyder at K-State. Before him they were terrible, when he left they were better but slipped back to the pack and almost to mediocrity, and when they got him back they became a national contender again.
Just pointing it out not as an excuse having anything to do with our present situation or Bruno95's very worthy question which I think he answered very well himself, but just what is historic reality for just about all programs.