He chose Southern Miss because that was one of the only D-1 schools that would've had him on the field as a freshman due to his grades... he may have had to go the JUCO route had he signed with one of the SEC schools who were recruiting him...
As far as physical talent/tools, he belongs right there in the top 5 WR's in this draft... he has better size than Jonathan Baldwin, but he's also more fluid, more sudden, and quicker than Baldwin.
He's Alshon Jeffrey physically, but he's had a rough go of it since his monster freshman season.
DeAndre Brown has many of the same type question marks surrounding him the Mike Williams had last year, except Brown didn't quit. He's the type of prospect that warrants a team taking a chance on his incredible talent in the draft, but it'll most likely be late due to injury concerns and questionable work ethic.
Guys that remain healthy and produce in college with DeAndre Brown's size, speed, and physical talent are top 10 prospects in any draft, and usually the #1 wide receiver on the board...
A kid like this can be drafted in the 5th/6th round or so, and end up starting for a team and producing as a rookie, the same way Mike Williams did last year.
If he gets it together, he has pro-bowl ability... If he doesn't, he'll be out of the league in no time.