When I watch Strong on tape he doesn't play that fast. He struggles sometimes to get separation and that comes from poor route running. Speed is not enough...just look at Percy Harvin...I think Harvin averaged 6 yards per reception in Seattle with a pretty good deep ball thrower in Russell Wilson. I also don't think Strong wins enough in the red zone...with his speed and vertical he should be unstoppable in the red zone but one of his games...might of been Arizona...he lost more red zone opportunities than he should have.
Strong is raw...not as raw as DGB or Coates but he's raw...he's got room to improve so he's not a finished product but that also makes him a borderline starter in the NFL on day 1. For a team that's really hurting for WRs he would probably start...on a team like the Packers where they have Jordy Nelson, Randall Cobb (if they bring him back) and Devante Adams he'd be the 4th WR on that roster.