Walker signed with the Saints as an undrafted free agent out of Tulsa in 2012. He made the roster but did not take the field as a rookie. Walker played in seven games in 2013 with four tackles and a sack and became a regular in the Saints defensive line rotation the following season, making 19 tackles and 2.5 sacks.
Walker signed with the Lions before the 2015 season but broke his fibula after only four games that season, and he underperformed last season, going from starter to a reserve player and was even benched for a midseason game.
Walker, 27, played 353 defensive snaps in 2016. He appeared in 15 games, finishing the season with 26 tackles and no sacks.