The Buffalo Bills had two of the top ten corners last season as ranked by Pro Football Focus in Ronald Darby (4th) and Stephon Gilmore (9th). The two of them helped hold the Bills opponents to a 57.6 completion percentage which was third best in the league.
The talent at the position was extremely top heavy and dropped off after them. Nickell Robey did a good job in the nickel role for the team but he is not even close to the caliber of the other two.
The Bills did have two safeties last year who were former cornerbacks in Corey Graham and Leodis McKelvin.