DJ Stephens has great NBA potential as you can see from some of his summer league highlights with the Miami Heat. He has a massive vertical and is so explosive and lengthy to go along with an incredible motor. One ting that could hold him back is his sports asthma that limited is minutes somewhat at Memphis.
I believe that DJ Stephens could be the most explosive and possess the highest vertical in the NBA while the only other guy that comes close is Gerald Green and James White when he was in his prime. What sets Stephens apart though is that he has a great impact on the defensive end and is a relentless hustler which makes up for his mediocre shooting ability. He could become a lockdown and impact defender in the NBA for a team which is always needed.
I think some NBA comparisons for him would be Chris Birdman Andersen but Stephens plays small forward sooting guard he has the same defensive impact and hustle. Another could be a Tony Allen, who is more Stephen's size, but DJ is a better shot blocker.