I used the term "magic coach" when we in the period of the Pelini divorce. It's pretty clear that we didn't hire one of those. Consistency across the roster was coming apart under Pelini. Regardless of who is the coach, that needed to be addressed and still needs to be addressed. We need more difference makers. JD Spielman shows signs of being one. Possibly Carlos Davis. There may more from the younger side of the roster that emerge in the next year.
This is how I see it:
Callahan left some difference makers on the roster and some other kids who were ready to play good FB. Pelini added some to the mix, but recruiting busts and attrition got things out of whack. Eichorst hired the anti-Pelini and (I am now speculating a bit) thought the hire could win 8-10 games at NU, just like Pelini did. Riley proceeded to bring the bulk of his staff to Lincoln and then last year realized he had to up the ante to stay on board. So in year three we shift from a QB in TA that could at least make money with his legs to a statue, go full up with Langs O, and make a substantial shift to a 3-4 with players recruited to a 4-3. And it's pretty clear that regardless of what kind of offense or defense we play, we have a roster that is not sufficient to consistently compete with the top end of our league.
The new AD will decide Riley's fate at season's end. Regardless of whether he is retained or not, work remains to be done on the roster. But we are not in an "existential crisis". If retained, Riley and Diaco will attempt to improve the players on the roster and recruit new ones and we will play a season next year. A new coach will bring in a new staff, possibly bring some recruits with him and begin to transition the team to whatever systems he uses. Then they will play a season next year.
I am disappointed with the play of the team this year and I concede that those who call for a coaching change have a rationale for their stance. But regardless of who is coaching this team, we need more athletes on the roster to compete with the class of our league.