Joe Paterno = Tommy Tuberville?
I've never thought it that directly, but many, many times I've thought that we'll never know.
Back in December of 2008 when talk of Tuberville leaving was being tossed around, I made list after list after list of examples of why we should keep him and give him a chance to turn it around.
Just like the guys you listed, they all (except Osborne) experienced those dips. From 67-70, Bryant won 8, 8, 6 and 6 games. After having won 11, 10, 9, 10, 9 and 11 games the previous 6 years, he was obviously slipping, washed up, had lost touch with the kids, the game had passed him by....and whatever other career ending phrase you want to insert.
He was done...finished.
Well, except for the fact that he wasn't. He won 11, 10, 11, 11, 11, 9, 11, 11, 12, and 10 games in the next 10 years.
Tuberville went 9, 8, 13, 9, 11, 9, and then 5. Would he have gone back to 11 or 9 or 13 in the next three years? We'll never know. But think what Penn State would have missed had they given up on Joe Pa after he won 7 games in 1970. Or when he won 7 in 1976. Or when he won 6 in 1984. Or when he won 5 in 1988. Or when he won 5 in back to back years in 00 and 01.
The list of "down" years by great coaches is long and includes a lot of hall-of-fame names. I'm over it now, but I did used to wonder what might have been had we let Tuberville try to fix his 5 win season and situation. Rumor was he was willing to clean house on the offensive side. What if he had and hired Malzahn?