Mark Dantonio's record in his first three seasons at MSU was only a little better than where Mike Riley's is about to be. Wasn't until year 4 that he turned the corner and made the jump.
Dabo Swinney, if you count his year as interim head coach (I do, since he coached over half the season), went 6-7 in year 3 and needed until year 4 to win a conference championship, but even then, only finished ranked #22.
Jim Harbaugh had back to back 10 win seasons in his first two years, and is having his worst season thus far in year 3.
Mike Leach didn't get WSU turned around until year 4.
It took Mike Gundy until year 4 to have a top 25 season, and until year 6 to have a top 10 or double digit win season. Year 7 for a conference title.
Art Briles didn't get Baylor to full potential until year 6.
Baylor, KSU...even WSU to a lesser degree....these types are notable exceptions. They are literally building a program from the trash. Yes, they all take that 5-6 years to get there. They are also not analogous to Nebraska's situation.
Dantonio was Year 4, not a big stretch in this argument, but he made strides those first three years, not as much in wins but in performance. Riley didn't, when you look at the actual metrics. Riley didn't make the jump his second year, he merely underperformed his first year. You can actually make an argument his first year is his best year. When you look at the metrics, year 1 and 2 are very similar, but year 1 had those close losses. Would I have fired Dantonio after year 3? No. He was averaging +0.9 YPP difference, a good number, and better than you'd expect with his record. Riley is at -0.3 this year and at -0.1 last year. Dantonio therefore comes down to how big of a deal you think one year is in a coach that was showing improvement, and if you think he's built a top tier program. I don't think he's analogous to Riley, at any rate.
Dabo: I don't even know why he's on the list. 3 years, 3.5 years, whatever. We are drawing at straws on this one.
Jim Harbaugh is replacing 20000 NFL draft picks, and still has a top tier defense in yards and scoring. You really don't think Harbaugh has shown he's a guy that can take Michigan to the elite level? If you do, fine, I can certainly that, but I think he's more example than exception. Three years and so far his worst is .769.
So far, I'd say Dantonio depends on how strict you want to set the parameters, Dabo and Harbaugh are not exceptions, and the remainder are not analogous to the situation we've described. Gundy is interesting though.
He's clearly not in a Baylor/KSU type scenario, after all Les Miles had that team to a decent level. Gundy did have them going good, though not consistently at year 4. My question is really then, does he qualify as a coach of a top tier program. That's specifically what we are looking at, not just a 9 win plateau type team (ie Pelini). What does it take to bust through that and get back to where we want to be. I'd argue to some degree that Dantonio doesn't fit this either, though not to the degree of Gundy. To me, Gundy is in that plateau and hasn't shown he can be that guy. Opinions may differ, though.