He would easily have been RC Slocum's heir-apparent, and would have fit in better with their culture.
Instead, he tried to change ND's culture, and the rest is history...
His critical mistakes:
1) Hiring Jim Colletto as the OC. Colletto tried to turn a power-option team into a run 'n shoot team.
2) Sticking with Kevin Rogers for all of that time. Rogers was all too predictable, and didn't even bother making adjustments in that 2001 Fiesta Bowl, where the Oregon State defenders were already calling out the play we were about to run before we even snapped the ball.
3) Not giving Urban Meyer a fair shake. I will say this, that Meyer is a sleazeball, but had he been given a chance to strut his stuff at ND, I think that there's a chance he could have turned out differently.
4) Firing Joe Moore. That single-handedly demoralized the offensive linemen, and when some of the GA's protested, he simply told them "he's too old. Get over it!" While the offensive line wasn't awful during that time, it wasn't anywhere near the standard set during the Holtz era.
He wasn't without merit, though. He did build a solid defense that carried his teams throughout the years, and even gave Lionel Tyrone Wilingham a year of glory...