CBS Sports has Street as the 21st best receiver in the draft and projects him as a fourth-round selection. NFLDraftScout has him exactly the same - the No. 21 receiver and a fourth-rounder. NFL.com gives some analysis including a few strengths and weaknesses, before calling him a fourth- or fifth-round pick.
Seeing Street slip beyond that wouldn't be much of a surprise to me. There have been other Pitt players that dropped below where I expected them to go and the Draft is such a difficult thing to project. Teams get enamored with players only to change their minds. They may fully expect a player at a certain spot only to see a higher prospect drop and go in a different direction at the last second.
One piece of good news for him is that he certainly helped himself with Pitt's pro day, by all indications. So much focus goes into the Combine, but things like schools' pro days area also great chances for players to perform.
The biggest issue for him is that I'm not sure he does any one thing at an elite level. The positive is that he just finds ways to get open and even in dealing with a new quarterback last year, still had an amazing year battling through some injuries.
The New York Jets' site may say it best:
Devin Street, Pittsburgh — Another 200-plus-catches guy, he’s a big target at 6'3" and 200. Not exceptionally fast but catches everything in his reach. He'll fight for contested balls and for every yard after the catch.
Street certainly has value, though, and by all indications, will be selected. Now, it's only a matter of finding out where.