A guy like Christopher will get a lot of feedback from scouts. There’s nothing special about him that needs to be hidden, and if there was, other people will discover it in private workouts and on film, anyways. If you followed Hardin when he went through this process he got a lot of feedback.

http://www.draftexpress.com/profile/DeVon-Hardin-225/

In an interview on that site:
Why did you decide to enter the NBA Draft last season, after playing only 12 games?
Hardin: I entered the draft just to basically see where I was, and where I was in comparison the other premier players in the country. I wanted to get feedback from NBA scouts, NBA general managers…not just scouts, as to what I could work on for this upcoming season. It was a consideration at one point to keep my name in there because I was getting such good feedback, but I figured I’d go back to school for another year and if I get a solid year under my belt, I could really make some good things happen this year.

What seemed to be the feedback that you received from NBA GM‘s and scouts in regards of what you needed to improve upon most?
Hardin: Improve my shot. Be more consistent with my shot. Consistency on offense was the main point that I got from the coaches. Physically, they say that I am very dominating over most of the big men that I was playing against in the camps. Offensively, they said I just need to develop a little finesse, and a little more touch around the basket. That was the general feedback. You can’t dunk everything.

Teams will try to hide who they’re going to pick in an upcoming draft, but there’s no incentive for them not to give a player working out for them tips on what his biggest weaknesses and how to improve them. It can even be benefitial to the team if they tell the player what to work on and over the course of the workout process or the next season notice an improvement in those areas. They’ll discover how coachable the kid is, whereas other teams may not work with the player and find that out.