Assuming your premise is correct, this still doesn't explain the lack of creativity on both sides of the ball, consistently poor special teams play, the inability or unwillingness to put what you have (Tommy), in the best position for him to succeed, lack of offensive continuity in style and personnel, etc...
ND was not oversold on Kelly he has done a good job, in fact, maybe better than some expected, but that doesn't mean he should get a pass on everything, and it doesn't mean he should not have to continue to grow. I think everyone is so quick to blame everything on EG not being here. In the coaching profession that is not an excuse, Coach always says, "Next man in", but if the next man isn't an EG clone maybe part of the transition has to be an identity overhaul, if you are not willing to do that, then you are passively wishing that the other guy was here doing what you want to do, but that isn't reality, that isn't next man in. Then, all you are left with is excuses and "what could have been's" if this guy was here or that guy wasn't injured. As I understand it that is NOT "next man in" thinking, I thought it was accepting the reality that things change, the show must go on, and we will not make excuses, not that the next guy must be the same as the guy in front of him and if he isn't we'll blame it on the fact that I couldn't run my system.