He has proven throughout the years that he can get your program to be a relatively consistent top-10 contender.
He did it at Cincy, and also at ND (during Kelly 2.0).
That was enough to "satisfy" a lot of people's appetites, but it became more obvious that he wasn't going to take us any further.
The fact that we got wiped out in both of his playoff games showed how much of a gap there was between us and the upper echelon.
A lot of us, myself included, held onto the hope that he could take another leap in capability like he did in 2017 (Kelly 2.0), and that maybe, just maybe, he'd get us to being able to regularly trade punches with the big boys.
In 2021, it actually looked like he might have take us to that level (coaching us to what could have been a playoff appearance), but when he abandoned us in favor of his 30 Shekels of silver, and squashed our hopes of getting into the playoffs, that pretty much cemented the belief that we weren't going to get any better under his reign.
His influence still reeked after he was gone. In 2022, Tommy Rees said that we didn't need a transfer portal QB, and it cost us a playoff opportunity, and his bone-headed playcalling easily cost us the Stanford game (and others).