Well being from Oklahoma I've seen him play a number of times (Including live once) so I would rank him probably 4th best corner.
The thing is I think he could be a very productive 3rd corner (which we obviously need) and you could, at the same time, groom him for the safety position if you wanted to make him the eventual replacement for Roy.
The one knock I'd have is this. Much like with Roy you have to worry about how great his coverage skills really are cause he does play in the Big 12 where the passing offenses, while good, are not superior passing offenses. Thus why when teams like OU play teams like USC, Florida/Miami (In years past), and such they get eat up, badly, by the pass.
So I'd worry how good his skills really are.