You're missing the point with the Spiller pick...In essence, the Bills have added three players with C.J.: Running Back obviously, and kick/punt returner extraordinare. But I believe the FO is really projecting him to excel as a receiver. My guess is Gailey will use him as a primary receiver, not just a dump-off, back-in-motion option. We will certainly see him do that, but he will also be, effectively, the slot receiver at times. And don't be surprised if he sometimes streak straight down field. So Lynch and/or Jackson should be on the field most of the time.
Two other factors Spiller will bring to the offense: Headaches and fear. Because of his ability to be used in so many ways, and the potential to take it to the house every time he touches the ball, defensive coordinators are going to be pulling their hair out. And defensive players are bound to be on edge every time he's on the field, knowing they can be embarrassed at any moment. Which means they're going to be distracted and tentative.
If Hardy and Johnson come through as receivers this year, and if (The Big IF) one of the QBs actually performs well, this offense could be nutty. At a minimum, I think we'll see the Bills score-per-game increase markedly.