Originally Posted by mussop
A lot of the teams early in the second round are in need of a QB. Buffalo (example) may want to jump ahead of Arizona to make sure they get the one they want. Also teams drafting project QB's like the ones in this draft may prefer to have the player under a 5 year contract that comes with the first round pick rather than the 4 year one that comes with the second round pick.
OK, but that doesn't explain why they trade up to the Texans spot and not the Packers, Broncos, or more logically, the Ravens. I would think a team in the 2nd round looking for a d-lineman or DB would make mode sense as a trading partner, as those are the positions the teams behind the Texans are likely targeting.