Two, IFs. If Singletary is willing to sign for a cap friendly deal, and IF he is willing and able to play Special Teams, he can take Taiwan Jones roster spot (whom the Bills have not resigned yet.) Then Beane can draft a bruiser in the later rounds.
All good comments and valid points on resigning, not resigning Singletary. Personally, I like him and think he is a very capable back. Runs hard, good hands, blocks well, doesn't fumble much (13, lost 5, out of 817 touches) and a smart player. He has been a great team player.