The Texans biggest issue this year was not QB, but pass protection. Houston was 16th in sacks given up(42) but 31st in QB hits (113). Matt Schaub had 15 sacks against him in the first 6 games. This is a breakdown of the O-line for Houston,(taken from http://www.sbnation.com/nfl/2013/11/21/5129228/2013-houston-texans-matt-schaub-case-keenum-jj-watt-gary-kubiak I would suggest everyone to take a look at it as it breaks down Houston's issues in 2013 quite well).
This is why I believe if they trade down it will be for one of the first few teams, enabling them to still take one of the top lineman in the draft. If they ask too much and can't find a buyer, or decide to stay and take a tackle with the #1 pick it will make our pick that much more valuable.