The only question mark the Bills have is they have no secondary weapon that really gives an opposing D pause like the Bengals do. Davis and Knox << Higgins, Boyd and it's not even close. Not to mention the Bengals have a good 4th option in Hurst and Mixon is serviceable out of the backfield. This will be the thing that comes back to bite the Bills if they don't win this year. They really should have tried to go out and get those other guys more last year.
Edit: Forget to mention Beasley, but he is only okay and doesn't do enough as the potential #2. He really would be a #3 on a championship team.