CJ Spiller wasn't even close to the biggest bust. He scored touchdowns, had some big runs, and flashed big potential.
Maybin and McCargo weren't even good enough to be on the field, ever. Maybin had zero career sacks with the Bills and was so tiny the other team just ran at him every time he was on the field.
Mike Williams was the 4th OVERALL pick and couldnt even hold down a starting guard role. Probably have to go with him just because he was such a high pick.
Losman and Manuel set us back, but at least they could hold down a backup job. Honorable mention goes to Erick Flowers and Reuben Grant. That's just recent guys.