I suspect part of Milton's problem is... for lack of better word... "excitability". The overthrows are probably a mental issue more than mechanics. So, it would make sense that he would look much better in mop-up duty where there's nothing on the line and not much to get excited about.
But put him in with a chance to drive down the field and win the game...? He runs out of bounds after time has expired. Excitable.
I may be wrong, but I won't give him the benefit of the doubt until plenty of proof in pressure-filled, game time situation. If he starts next year, I suspect it will be out of necessity, and the overall results won't be much more favorable.