Manuel was benched after four games in 2014 after completing 58 percent of his passes for 838 yards, with five touchdowns and three interceptions.
Whaley said that the upcoming season will be critical for Manuel, whom he lauded for his work ethic.
He knows this is his make-or-break year. This is his time to step up and show everybody he's got a clean slate with a new coaching staff. It's his time. He's dedicated himself. He's working with Steve DeBerg in the offseason. The one thing we know is he's going to work his butt off, and he's committed. We'll see how the chips fall.
On Monday, Whaley said that he doesn't feel the team has a franchise quarterback.
"The way we looked at is, we don’t have a proven franchise quarterback," Whaley said, according to ESPN. "That’s obvious."
After being selected with the 16th pick in the 2013 draft out of Florida State, Manuel played in 10 games as a rookie, throwing for 1,972 yards with a 58.8 completion percentage, 11 touchdowns and nine interceptions.
The Bills acquired former Patriots, Chiefs and Vikings quarterback Matt Cassel in a trade this offseason. In addition to Manuel and Cassel, Buffalo's roster includes quarterbacks Tyrod Taylor and Jeff Tuel.
Whaley has been Bills general manager since May 2013. He was assistant general manager when the team drafted Manuel.
In January, the Bills hired Rex Ryan as head coach.
Buffalo is one of only two teams without a first-round pick in the NFL draft.
- Alex Putterman