Sherman and Sam Shields have both done a terrific job at CB after converting from WR. Most guys are just too proud to switch to covering instead of catching and overrate their WR abilities. I wish more College coaches would convert WR's into CB's. I think their experience on the other side of the ball helps them understand and read routes better.
Good time to pick a developmental CB though in White. Not really any other type of CB's available at this point. Plus, you got another guy who you think is going to be better than his draft position.