Nix was the Bills general manager since 2009.
The Bills are coming off a 6-10 season. Buffalo's 13-year playoff drought is the NFL's longest active streak. The team has not had a winning record since 2004, when it finished 9-7.
Tight end Dennis Pitta signed his $2.023 million second-round restricted free agent tender with the Baltimore Ravens, the team announced.
Pitta had interest from the Miami Dolphins and San Francisco 49ers, according to the Baltimore Sun, but neither team presented Pitta with an offer sheet.
The Pistol offense has invaded the NFL, and now its creator -- retired Nevada coach Chris Ault -- is joining the league, too.
Ault, 66, was hired as a consultant by the Kansas City Chiefs, his agent, Bob LaMonte, told the Reno Gazette-Journal.
Ault's most famous pupil is Colin Kaepernick, the former teammate of Chiefs' quarterback Alex Smith.
Defensive lineman Brandon Deaderick, who started five games for the New England Patriots last season, was released by the Patriots on Monday.
The move was not expected, because Deaderick, 25, played in 14 games, including those five starts, in 2012, when he had 10 tackles, eight assists and one sack.
Michael Vick, the team's most grizzled veteran at 32, and second-year pocket passer Nick Foles split first-team snaps with the Philadelphia Eagles offense in drills and simulated scrimmage situations.
Vick said the quarterbacks are not worried about who is the No. 1 quarterback in May. He plans to stress consistency and making the right decisions while grasping Chip Kelly's vast scheme.
Jacksonville Jaguars wide receiver Justin Blackmon said that the two strikes against him in less than one year in the NFL doesn't mean he has a drinking or substance abuse problem.
"I would say I don't," Blackmon said. "Out of this whole thing, one of the main things I would say that I had a problem with was just making a poor decision. Making a selfish decision at that, not thinking about the long-term of it ... If you want to ask if I have a problem, I have a problem with making a poor decision."
The Kansas City Chiefs announced that they signed running back Knile Davis, whom they selected in the third round of this year's draft.
Davis rushed 349 times for 1,862 yards with 19 touchdowns and made 32 catches for 297 yards with two scores in three years at Arkansas.
The Washington Redskins announced they signed two of their draft picks: fifth-round linebacker Brandon Jenkins and sixth-round safety Bacarri Rambo.
Washington also waived wide receiver Jason Thompson.
The New Orleans Saints announced they signed six free agents to contracts after the team's rookie minicamp over the weekend.
Defensive end Baraka Atkins, wide receiver Brent Leonard, defensive back Korey Lindsey, kicker Jose Maltos, running back Khiry Robinson and guard Jeremiah Warren signed deals. The Saints also waived running back Shawne Alston, cornerback Ryan Lacy and center Ryan Lee.
The Cincinnati Bengals signed two draft picks and waived a player from their roster.
Cincinnati signed fourth-round linebacker Sean Porter and sixth-round H-back Rex Burkhead. The team waived rookie defensive tackle Travis Chappelear, a free agent.
The Oakland Raiders signed seven players who tried out with the team over the weekend and claimed wide receiver Andre Holmes off waivers from the New England Patriots.
The seven players signed were cornerback Chance Casey-Thomas, linebacker Eric Harper, wide receiver Greg Jenkins, tight end Jeron Mastrud, defensive end Ryan Robinson, center Andrew Robiskie and cornerback Mitchell White.
Cornerback Adrian Bushell, center Deveric Gallington, defensive back Akwasi Owusu-Ansah, tight end Mickey Shuler and long snapper Adam Steiner were waived.