PITTSFORD, N.Y. -- Coach Chan Gailey can do the math rather easily: The Buffalo Bills have two capable running backs, and only one football to go around.
"I said this way back: 'Everybody that is supposed to touch the ball won't be happy, because nobody's going to get it as much as they would like,"' Gailey said. "It's a little bit of a problem to make sure those guys touch it as much as they need to. But it's a good problem to have."
Jackson can sympathize with Gailey's dilemma.
"I'm glad I don't have to make that decision," Jackson said, regarding playing time. "So long as we're winning football games, we'll be all right."
Spiller's on board, too.
"We both understand that we both can't be selfish," Spiller said. "And if we're both playing at a high level, then it will elevate our team. It's exciting."
The Bills (No. 19 in the AP Pro32) have high expectations approaching this season, and part of that revolves around an offence that returns mostly intact after finishing a respectable 14th in the NFL in yards gained last year. It's a Gailey-run attack that relies on its running backs to play a key role in both the ground game and as receivers to keep opponents off-balance.
Though the two running backs have been together since 2010, when the Bills selected Spiller with the ninth pick in the draft, this marks the first season they're being regarded as relative equals.
Jackson, the veteran stalwart, was the team's first-half MVP in helping the Bills get off to a 5-2 start before his season ended in November, when he broke a bone in his right leg. Through seven games, Jackson was fourth in the NFL with 721 yards rushing and second with 1,074 yards from scrimmage.
Having signed a two-year, $9 million contract extension this off-season, Jackson has both the respect he's long desired from the Bills, and also the drive to show last year was no fluke.
"I want to show that I belong as a 31-year-old running back," Jackson said. "I want to go out and show why they showed faith in me, and why they kept me around."
Spiller has something to prove as well. He's eager to show he can build off what he did in showing flashes of his potential in filling in for Jackson over the final six games last season. Enjoying his most playing time since arriving in Buffalo, Spiller averaged 74 yards per game and scored five times, including two touchdowns receiving.
It was enough for him to finally feel like a true contributor after managing just 283 yards on 74 carries in 14 games as a rookie.
"I never lost confidence in myself. I think the fans were more concerned about it," Spiller said, referring to questions about his initial lack of playing time. "But I don't think anybody in the organization was worried about my abilities. It was just that we had a guy playing a Pro Bowl level. And when you have that then coach Gailey obviously kept with him."
Jackson is more of a straight-ahead runner, who's capable of pounding out yards against opposing defences. Spiller is smaller, and more elusive, relying on his breakaway speed to beat opponents.
Their one-two punch has been on display in training camp, ever since the Bills began practicing in pads last weekend.
On Wednesday night, Jackson punched his way through a hole on the right side. A few plays later, Spiller went left, and found a crease for what would've been a big gain.
Spiller is also getting more time in pass situations. On Thursday, he sneaked out of the backfield and found himself wide open in catching a pass in the right flats.
Gailey has stuck with his plan to share the load so far. Jackson and Spiller have both been getting near-equal practice time, runs and catches with the starters in team drills.
And Gailey hasn't ruled out coming up with a rotation or even having them line up in the backfield at the same time once the season begins.
"I don't want one of them standing over by me too much (on the sideline), because they're both such good players," Gailey said.
NOTES: Free agent safety Jim Leonhard visited the Bills and watched practice from the sideline. Leonhard was released by the Jets this off-season after tearing a tendon in his right knee. He spent his first three NFL seasons in Buffalo, after making the team in 2005 as an undrafted rookie free agent. ... DE Chris Kelsay was held out of practice to nurse a minor groin injury. S Bryan Scott (thigh) and DE Mark Anderson (groin) practiced on a limited basis. ... The Bills signed undrafted rookie free agent RB Zach Brown. He replaced undrafted rookie RB Chris Douglas, who was waived after getting hurt in practice Tuesday. ... QB Ryan Fitzpatrick completed two deep passes, hitting Derek Hagan on the run over the middle, and then hitting Stevie Johnson in stride on a post route.