Every players gets a 'we should sign him' thread. I'm glad this one has been fulfilled and can die now. If you think he's going to be an upgrade, time to take off the 'every player not on the Bills is better than the Bills player at that position' glasses.
Peter King's column addresses this issue. He spoke with a former NFL player who now studies depression in players. http://sportsillustrated.cnn.com/nfl/news/20130115/nfl-playoffs-peyton-manning-peter-king/?sct=uk_t12_a5