To me, Dunleavy's situation was the opposite of Mark this year. Dunleavy was rated higher than he should have been because his weaknesses were hidden by a fantastic roster 2 years in a row. At the very least, he had very little room to improve his stock.
If he stayed, he faced 3 big risks. One, not being able to carry a team that lacked the talent and experience of the previous team. Two, being outperformed as a senior by a couple of freshmen-Reddick, Williams, and Randolph. And 3, injury.
Mark, on the other hand has a great opportunity to vastly improve his draft stock, if for no other reason he is projected to go so much lower. The improvement of Roach and the addition of Paolo and Griffin could very reasonably make Mark impossible to scheme for. Next year's team should be better in every facet of the game. This should only wind up helping Mark and his draft stock.