Let's be honest: the offensive line probably isn't a very high priority in terms of draft needs for the Dallas Cowboys. That's because they have one of the best lines in the entire NFL.
Owner Jerry Jones underwent some sort of renaissance in 2011 when he selected left tackle Tyron Smith with the ninth overall pick. After that he took Travis Frederick in the first round of the 2013 draft and Zack Martin in the first round of the 2014 draft.
Dallas is set at left tackle (Smith), center (Frederick) and right guard (Martin). Their biggest areas of concern on the O-line would be life after Doug Free (the right tackle's deal runs through the end of the 2017 season.