Hill is a rare breed. Not only is he 4.2 fast, he can take a hit and play physically as well. Watch him with the ball in his hands, he looks like a running back.
That's what screws over a lot of speed guys. Tavon, for example, was low-4.3 fast and had jitterbug quickness, but he can't handle any kind of contact. You feed him a bubble screen on 2nd and 5, he's going down as soon as a DB hits him. You feed Hill a bubble screen, he's putting a stiff arm in that defender and fighting for the first down.
Henry Ruggs is in that same kind of mold too - he gets after guys. Hell, he puts more effort into run blocking then half the college TEs I saw. Dude is going to be a stud.