People expected too much from Shumpert on the offensive end. For someone with his athletic ability, it's a shame how limited he is on that end of the court. A competent coach could get the best out of him though. If it's true that Phil really likes him, he might stand to gain the most from the regime change.
He also tends to be over-aggressive on defense and makes a ton of mistakes because of that. He's good (not great) on that side and has the tools to become a consistent shutdown defender but he's definitely not there yet despite what others might lead you to believe.
Potato head and the Knicks org really didn't do him any favors. Always holds him accountable for every little **** and makes sure to let him & the media know it but vets like JR get away with a lot. For an emotional player like Shump that becomes a huge factor.