There was no cornerback that the Cowboys could afford that was worth a free agent pick, imho. Diggs just got here, shows lots of promise. That's at least as much as a draftee has. The do have Lewis, etc. I don't agree the Cowboys "have" to pick a cornerback, there's needs all over the defense, even if they got a corner and he magically turned into Deion Sanders, the team is very unlikely to be going to the SB without more improvement at other positions.
This is a non-story, I will GUARANTEE there will be an excellent player at 10 (assuming Dallas doesn't trade down) that can be a big help to the Cowboys...