Which Maryland basketball player has the highest NBA draft stock?

There's been a lot of talk on this site, on Twitter and all over the place about what Maryland basketball players are or are not NBA prospects, who might or might not leave early and what skills are or are not coveted by professional teams. I figured it would be a good idea to ask a draft expert to break it all down for us, so I turned to CBS Sports' Sam Vecenie (@Sam_Vecenie). Sam is an Ohio State graduate who does a fantastic job writing primarily about college hoops and the NBA draft for CBS. Here's his top 100 NBA draft prospect Big Board for reference.
I started with some more general questions about scouting college players for the NBA and the Big Ten as a whole before getting into the nitty-gritty on the Terps.

On what seperates an effective college players from an NBA prospect...

To me, the biggest thing that I look for are elite talents. Can this guy do at least 1-2 things on an elite level on the basketball court that can help him translate to playing an NBA role? Because with most college kids, that's what they're going to become in the NBA. There are very few stars in the NBA who can carry a franchise. Every team needs guys like a Danny Green, Draymond Green, or even like a Brandan Wright. Be it shooting, rebounding, protecting the rim, playing stellar perimeter defense, etc. A lot of ways that guys can make an impact, but to make it in the NBA you have to be pretty damn close to elite at it.
Obviously, there are specific skill sets that you're looking for at each position. Big men who can rebounds, guards who can shoot, centers who can block shots, etc. However, with the way that the NBA is going towards up-tempo, position-less basketball, those skill sets are starting to change. So that's where I would refer you back to the previous question by saying I look for specific, elite skill sets that can translate to playing a role. Big men aren't just rebounders or defensive players anymore. Maybe they can be floor spacers that make it so fewer people are in the lane for attacking guards? So I'd say being able to fall into a specific role with your skill set is more important than looking for something with guards, wings, bigs specifically.

On who he sees as the top NBA prospects in the Big Ten this season...

The best prospect in the Big Ten, for me, right now is D'Angelo Russell. He's an intelligent-beyond-his-years freshman who can knock down shots from the outside, and throws crisp, intelligent passes that veritably make plays for his teammates. But that alone isn't what makes him a top-seven prospect in this draft class. His ball-handling skill is tremendous, as he has really strong change of speed and change of direction. His IQ is just tremendous on the floor. He's somewhere between a cross of James Harden and Deron Williams in my mind with the way he plays. I don't know that he ever reaches those lofty, all-star level heights, but I think we're looking at a legitimate, NBA starter caliber guard at the worst. Behind him, I'd put Frank Kaminsky and Caris LeVert* both as potential lottery picks (Kaminsky is 13, LeVert 15 on my big board), and Sam Dekker as a guy I'm less high on, but ultimately still have in the mid-late first round.

*This interview was conducted prior to LeVert's season-ending injury, although he's only slipped to 16th in Vecenie's rankings.

On Maryland's best prospects, for both 2015 and beyond...

Man, that's a really good question. I'd probably go Melo Trimble, and I think he's a potential first-rounder down the road. The explosiveness in blowing by players into the lane is really superb, and I think his ability to get to the free throw line is absolutely going to translate. Still, I think he probably needs another year in school to work on really getting his jump shot to where it needs to consistently be, and to work on his distribution skills when running an offense. A 1.16 assist-to-turnover ratio isn't going to cut it in the NBA. Becoming a smarter passer and slightly better decision maker is the difference between him being a second-round pick combo guard and a mid-first round pick point guard.
As far as his skills are concerned I would say that he should stay at least until he can become a more reliable decision maker who can get everyone involved in the offense. It's more of a game sense thing than it is a skill set thing. He has the talent to do it, it's more just getting the experience.
As far as Jake Layman is concerned, I'm not as high on his NBA prospects as I know some others are. I just don't know who he guards in the NBA. I think he's probably a bit too slow to guard on the perimeter consistently, and a bit too skinny to defend in the post. He's an incredibly intelligent, skilled offensive player though. I wouldn't put it past him carving out a role, but he's a second-round type guy at this point that would need some time to develop.
If his stock is higher than I am on him and scouts have him as a borderline first-rounder (like Jonathan Givony has him on Draft Express), then I think he should leave. Even so, I'm not sure how much more he can develop at Maryland than he has already. Even if he isn't an NBA player next year, it might just make the most sense financially for him -- depending on his situation -- to go. Even someone likeLaQuinton Ross, who left early and was undrafted, is still making six-figures over in Europe. So it's all dependent on what his priorities are, basically.
I've never been a big Dez Wells fan, to be honest. Think he often tries to do too much for his skill level, which results in poor shot selection and turnovers. He certainly has the athleticism and physical tools to play in the NBA, but he needs to become a smarter decision-maker. I wouldn't be totally flabbergasted if he eventually got a 10-day deal in the NBA after strong D-League performances, but I don't think he'll get drafted this season either.
As far as Robert Carter is concerned, I'll be interested to see how he returns. He's slightly undersized at 6-foot-8 to play the 4 -- despite his 7-foot-2 wingspan -- so I think his best bet is becoming a knockdown mid-range shooter if he's going to get to the NBA. But I'm definitely in wait-and-see mode with him.

On NBA comparisons for Trimble and Layman...

An NBA comparison for Trimble? Oh man, I hate doing these typically. He's similar athletically to a Jeff TeagueI think. And Teague had similar problems with assist-to-turnover rate in college. But he also has developed far above and beyond that into a borderline all-star this year. That's the development path that I think would be ideal for Trimble, if things go right. Having said that, it's all so dependent on where he would be drafted.As far as a comparison [for Layman]...It's tough to find one for him, because he's more SF than PF. The ideal guy you'd be praying to get with Layman is Chandler Parsons, and their games aren't too dissimilar. But that's the absolute best-case scenario, and again it would depend on how he developed after being drafted.