In prior 2012 NFL Mock Drafts the Dallas Cowboys have been projected to take a defensive back or an offensive lineman. However, over at the Sporting News they have the Cowboys taking an outside linebacker with their 14th pick:
14. Dallas Cowboys: Zach Brown, OLB, North Carolina Tar Heels: With Anthony Spencer likely to leave as a free agent, the Cowboys have to find a player who can rush the passer effectively opposite DeMarcus Ware.
At North Carolina last year Brown had 105 tackles, 13.5 tackles for loss and 5.5 sacks. All of those stats were near the top of the ACC for defenders. So, drafting Brown to be a pass rusher looks to make sense as long as he can continue is production at the next level in the NFL.