Generally speaking, you shouldn't draft TE's Top 20. Pitts is different, because he's proven to be a dynamic receiver - out wide, from the slot, and in-line, and he's done it vs the best competition CFB has to offer. Don't even think about putting a Safety or a LB on him, but if you want to put your CB1 on Pitts, he'll **** him up, too.
He separates vs press, separates vs off, catches everything, and is dynamic with the ball in his hands. In terms of speed, I'm hearing 4.4's, but even if it's low 4.6's (which would be disappointing relative to how fast he plays), that's plenty fast for his size.
I also think he'll be a plus blocker pretty early in his career. He's on that trajectory.
Regarding the #3 pick, that should be QB or trade down. Period. If forced to draft a non-QB at 3, though, Pitts would be my choice. He's the rarest talent in the class. I also think Smith and Waddle will fall out of the Top 10, so you could move up from 18 without giving up too much to come get them. Don't think Pitts makes it further than #8. He and Chase are the skill guys I expect to go earliest. Miami trading down to that 6-9 range, drafting Pitts, then drafting either Smith or Waddle would basically be a perfect 1st Round.