While I think there is much more to consider when discussing whether Fleck would be successful at ND, you do illustrate a good argument about his success so far.
One minor point though. FCS is not the old D2. Grand Valley State was then and is now competing at the D2 level. It is still called that. FCS is the old 1-AA as oposed to 1-A, which is now called FBS. Both were and are now D1. Kelly never coached at the FCS level.
Again, other than that, I think you bring a good point about what situations Kelly inherited vs Fleck and how they progressed once they were there.