Some of the responses in this thread are bewildering.
Yes, this is 100% the right move for him to make. He'll get feedback and will be able to compare himself to his peers in the combine to see where his stock is at.
He has 0% chance of going in the first round this year, but a very high probability of going in the 2nd round. NBA teams would love to draft a 20yo prospect with high upside and stash him in the D-league. The question is, does he want to sacrifice another year developing his game as the #1 player on an NCAA tourney caliber team to do that? (Note: This is where Ollie's pro-style offense is a HUGE upside for the program. Why would a player in his position come back to system that doesn't develop players/translate to the professional ranks a la Syracuse. Those players are better suited going to the D-league and playing in pro-style offense/defense)
Returning for his junior season at Uconn will undoubtedly increase his chances of becoming a first round pick in 2017. BUT, there are no guarantees. What is guaranteed is a 6 figure salary to play pro ball overseas waiting for him should he leave today.
Here is the most important and relevant info: Daniel Hamilton turns 21 in August. He essentially has a 10 year window (give or take) as a professional player to earn a living. Does he sacrifice a year of that, while risking injury, to come back to Uconn to improve his stock for a shot at the guaranteed 3-4 year contract that comes with being a 1st round pick? If he is told that he doesn't have a realistic shot at being a 2017 1st rounder, then he should go pro immediately. If he does have 2017 1st round potential (personally I think he does, mid to late), or if he wants to maximize his chances of making it to the NBA, or hell, if he just wants to further develop his game before jumping to any pro league, then he will probably return.
I think he does return in the end. Another year in school as the unquestioned leader and alpha dog, adding 10-15lbs to his frame, and working on his jump shot will certainly do wonders for his game. Do we have a shot at a title without him? Nope. Will I hold it against him? Nope. Hope he becomes filthy rich one way or another. He was the first big recruit to commit to Ollie/Uconn when the program was at its lowest and most uncertain - before that 2014 title run. Left California to come to cold Storrs and compete in a middling conference outside the P5. He's a Husky for life, a made man in mafia terms.