This is hardly the place, but here goes:
1. Fallacy #1 is that Marrone left this program in a healthy state. He didn't. He failed to recruit elite/very good offensive players at WR and QB. He then took all of the offensive coaches. You can make the case that he saw the writing on the wall and left while his stock was high - because he knew we were in trouble on the offensive side of the ball. ALSO: The defense has gotten better while Shafer has been HC.
So your contention that it "didn't need to get the kinks worked out" is a sad distortion of the facts. The train wreck on offense was obvious.
2. Shafer recruited defensive guys. The defense has been good.
He also pivoted from what Marrone was doing almost immediately to get players Marrone wouldn't take that year. So, yeah - he was on staff, but he didn't agree with Marrone's assessments.
This staff is light years better at recruiting than Marrones. Sure the wind is at their back being in the ACC and having the IPF, but they are doing pretty well. The proof of this is how many underclassmen are the future right now: Ish, Franklin, Cordy, etc. Where are the stud seniors?! (Answer: on someone elses team, because Marrone didn't find them, recruited JUCO too hard, etc.). Add in this years haul (only at what 6 players?) and it's crazy to think we won't be better in the near future. But the staff needs time to see that fruit.
3. I agree. This is the single worse decision he made as HC. He deserves all of the blame on that.