But running back Fred Jackson can't play forever. He turned 31 in February, and he had his 2011 season cut short when he fractured his fibula. Sooner or later, for better or worse, the Bills are going to have to find out exactly what they have in running back C.J. Spiller.
Is he a workhorse back who can carry the load? Or is he a dynamic back who is at his best when used sparingly?
The Bills' front office has claimed both to be true over the past 12 months.
In a 2011 Week 16 loss to the Dolphins, Spiller carried the ball 12 times for 91 yards and a touchdown, and he caught nine passes for 76 yards and another score. With a performance that strong, one might wonder why Spiller didn't get the ball more.
"We knew we were going to use C.J. a lot in the passing game," Bills head coach Chan Gailey said after the game, per The Buffalo News. "We knew that was going to be part of it so we're trying not to wear the guy completely out. He's not the biggest back in the world. I don't think he can go out there and carry it 25 or 30 times." (Emphasis mine.)
Although Spiller handled the ball a combined 21 times, Gailey's words indicate a lack of confidence in Spiller's ability to carry a heavier workload for the team's backfield.
"He could be an every down back," Gailey said, per ESPN. "I don't see any reason he couldn't carry 20- 25 [times] if he needed to. But he's a valuable, versatile player. He can play wideout. We're fortunate to have two very good backs. I'm going to try to make sure we keep them fresh and wear 'em out at the same time." (Emphasis, once again, mine.)
So, in summation, 20-25 good, 25-30 bad.
Perhaps the explanation is that the Bills don't feel he can be an "every-down back" in the traditional sense of carrying the ball 25 or more times in a game, but that he can play every down in their offense, doing everything from carrying the ball to blocking to catching passes out of the backfield.
Spiller has done a mix of all three since entering the NFL. But as of yet, he's had just one standout season. He played a decent role in the passing game as a rookie and flashed some potential as a kick returner with a touchdown against the Patriots, but when it came time to carry the ball, he was largely a let down, averaging just 3.8 yards per carry.
Then last year happened. An average of 5.2 yards per carry gave Bills fans something to cheer about, even as their season continued to unravel before their eyes.
"We always knew what we had," Nix said of Spiller, per the Buffalo News. "The opportunity is what he needed and he got it when Fred got hurt."
But will he get an opportunity like that again now that Jackson is back in the fold?
He may get some opportunities, but they may be fewer and further between than they were down the stretch last year.
"I can promise you this, we will not make everybody happy," said Gailey, per BuffaloBills.com. "That will not happen this year. The only thing that will make everybody happy is winning. That's what the goal is, to come up with plans that incorporate everybody's abilities that allow us to win. Other than that I can't predict what's going to happen as far as percentages for their touches."
They'll find out exactly what they have sooner than later. Spiller will likely get more touches than Jackson in some games, with the opposite holding true at other times. The fact that both backs are so versatile will certainly help each get on the field, and there are a ton of matchup problems that such a combination could create for opposing defenses.
Much like the Patriots with their two tight ends on the field at all times, the Bills can take a traditional running formation of two backs and leave a defense clueless as to whether it will be a running play or a passing play.
"The great thing about it is we can put both of them anywhere," said Gailey, according to BuffaloBills.com. "We can leave one of them in the backfield and put the other one out as a receiver or motion them out. They both can block well enough so they create problems for the defense, so it's really a good thing for us to have."
But it's only something they have right now. The present is clear, it's the future that remains uncertain.
For now, the Bills should enter 2012 with the focus of getting both backs involved and let the rest work itself out as the situation unfolds.