Here's something Ourlads had on DeCastro in their latest mock draft,
14 Dallas David DeCastro* OG Stanford 6047 316 5.32
DeCastro is the best guard we've evaluated since Steve Hutchinson in 2001. DeCastro is intense, explosive, patient, and has excellent recoverability in pass protection. Jerry Jones brought in Bill Callahan to coordinate the running game offense. DeCastro helps solidify the line in pass protection and in the running game. The Cowboys have signed two free agent journeymen guards but Callahan may consider moving DeCastro to center...he developed Nick Mangold into an all pro for the Jets.
EDIT: I could definitely get behind moving DeCastro to OC. I know he did work out some at OC at his Pro Day I believe. I wonder how his shotgun snaps are?