Cliff Avril is signed in free agency after playing his first five NFL seasons with the Detroit Lions. Avril finishes second on the Seahawks' Super Bowl championship team with eight sacks and also forces five fumbles during the regular season. In the postseason, he adds 1.5 sacks, two forced fumbles and puts the hit on Broncos QB Peyton Manning that leads to Malcolm Smith returning an interception for a touchdown in the Super Bowl. Avril added five sacks in 2014.
Pro Bowl linebacker Julian Peterson is traded to the Lions for defensive lineman Cory Redding and a fifth-round draft choice. Peterson had been signed as an unrestricted free agent in 2006. He started 47 games in three seasons with the Seahawks, and was voted to the Pro Bowl each season while producing 10 sacks in '06, 9.5 sacks in 2007 and 86 tackles in 2008.