Toronto, Canada – Buffalo, coming off a 6-10 season, fired Fewell and his staff earlier this year as part of an overhaul to return the team to the post-season.
"This guy met more of the criteria than I ever thought we could find. This guy has won everywhere he has been," said Nix.
"Very few times do you get an offensive-minded coach who has been a coordinator on defense, who has been a special teams coach in the NFL and has been successful everywhere he's been."
Buffalo's last playoff game was in 2000, when they lost 22-16 to the Tennessee Titans after a late kickoff return that remains one of the most infamous plays in the franchise's history.
(Writing by Frank Pingue in Toronto; Editing by Ken Ferris and Justin Palmer)