I just don't agree with your point. What Schiano did dragging Rutgers out of the muck WAS miraculous. He just never did anything to sustain or improve upon that level of mediocrity. But he deserves credit for taking the worst program ever in college football and making them semi-competitive. He doesn't deserve credit for anything more, because he didn't acccomplish anything more.
The same way that both of those standards apply to Marrone. He deserves a ton of credit for taking over a program that wasa national laughing stock and making us a helluva lot more competitive his first year [compare the PSU game from GRob's last year to the much more competitive game with Marrone at the helm the following year and you'll see the difference]. He then got us to, and won, a bowl in year 2. Pretty freaking amazing.
That he didn't stick around or help the program take the next step is stuff he can be criticized for, but those don't attract from what he accomplished when he was here. Did he make the team "excellent?" No. But he made them a bowl winner. Which after the declining P years and the GRob debacle was miraculous.