I don't mean this in a negative way at all, but I've always had the sense that Marques came into this season fully expecting to be a one-and-done. (
http://www.espn.com/mens-college-bas...ucky-wildcats: "My goal is not only to be drafted in the NBA but to play in the NBA," Bolden said. "I feel Duke will best help me reach my goal.") Sitting out the beginning of the season with Harry and Jayson (i.e., two sure-fire one-and-dones) and hearing the media group the three of them together probably added to that expectation.
I imagine that for guys who have a deep one-and-done expectation starting in high school, the idea of coming back for sophomore year is extremely unpalatable, no matter how much they love Duke/college. For most, if not all, of these high-level basketball players, the ultimate dream is BY FAR to play in the NBA, and they don't want to wait a second longer than necessary to make the leap.
Marques really is a mystery. It's possible that he ends up like the Harrison twins, who had absolutely no choice but to return for their sophomore years. I could see him entering his name in the draft, getting real feedback telling him that he should return to school, having a heart-to-heart with Coach K that motivates him to tear it up as a sophomore, breaking somewhat out of his introverted shell and playing great next year for Duke.
Or, that unpalatability of waiting another year to realize his NBA dream might drive him to stay in the draft and gamble on himself. Who knows, maybe a team will draft him on potential and he'll quickly develop into a productive NBA big man. If he does decide to leave this year, I hope his decision is based on wisdom and not impatience.
As for Chase, I assume your question doesn't have to do with whether he'll declare for the draft (I'm not going to use the "t" word). I think Chase is capable of playing at the high-major level, unlike someone like, perhaps, Alex Murphy or Olek Czyz. I hope he'll stick it out. I get the impression that he truly
loves Duke, which I honestly don't feel is true about every player who's come through the program.