West Virginia had one of the best offenses in the nation with Tavon doing what he was doing. They wanted Tavon to get the ball as much as possible, not send him deep. Since you just said that he catches well and is fast, what makes you think that he can't run deep? What skill do you think he is missing?
I'm not sure if he can get off press coverage. Like if he has to face a shutdown corner like Patton did in Jonathan Banks while in college.
And like I said I could name many guys who ran fast who turned out to be bust......check Oakland. Not saying that Tavon will be a bust, but just because you run fast does not mean you are automatically a deep threat in the NFL. Smith had the vertical leap and the yard average per catch to back up the thought that he MIGHT be a deep threat in the NFL. Also he was very tough for a lil guy, not to mention blazing fast.
I also don't think he can constantly take hits over the middle from NFL safeties, Percy barely does it and he is bigger than Austin.