Roy Williams 2002 was the only time Dallas drafted a S in the 1st round. He was a special impact player in college like Lott, Easley, and Berry. Other than that type of star player its a waste of a 1st or 2nd round pick to draft a S no.1 or no. 2 in a 4/3 D because the roles of FS and SS are so defined in a 4/3 D (everything is in front of you).
When Dallas went to a 3/4 D Roy Williams was lost because he had to carry coverage and the game was not in front of him to use his abilities and instincts.
Cowboys are still in position for Armani Hooker, Deonte Thompson, and some CBs are available which we really need with Jones, and Brown set for free agency. If they do go S, I like Armani Hooker.