If a QB starts to fall why would they wait for the 19th pick to trade up? They would do that closer to 15 IMO.
I've thought about that, and the logical place to trade up to is #18. Seattle has traded back in most of the last few drafts. Also, they don't own a 2nd or 3rd round pick. So, my "hopeful" scenario is unlikely. I do think that Buffalo may package the 21st and 22nd picks to move up for a QB.
What I think will actually happen is that the Colts may trade back with the Jets, and the Jets will move up to # 3 and get Colts get picks #6, #37, and #107. Then either the Colts or Buccaneers will trade back with Buffalo. The Colts, by trading back twice with the Jets and Bills, can end up with two picks in the 1st round (#21, #22), two picks in the 2nd round, (#36, #37), and 3 picks in rounds 3&4 (#67, 104, #107). With 7 picks in the top 107, it could be a historic draft for the Colts.
Then, Minnesota will trade up to #18, and the Seahawks will get picks #30 & #62. What that means is that 5 QB's will be taken ahead of Dallas, which leaves a greater chance that Vea or Derwin James will fall to #19. Those are my top two targets in the 1st round. And because of the depth at DT, James would be a better pick at #19 than Vea, in my opinion.