Silverstein cites the team's lack of comfort with the health of Collins' neck after an injury that required surgery and cost him all but two games during the 2011 regular season.
Collins sustained the injury on a scary play against the Carolina Panthers during the Packers' Week 2 contest and was taken off the field on a stretcher. He was later placed on injured reserve and missed the balance of the Packers season.
Originally a 2005 second-round pick of the Packers from Bethune-Cookman, Collins was one of the heroes during Green Bay's run to a Super Bowl XLV victory. His interception of Ben Roethlisberger in the Super Bowl, which he returned for a touchdown, gave the Packers a 14-0 first-quarter lead.
In seven seasons with the Packers, the 28-year-old Collins appeared in 95 regular-season games, totaling 417 tackles, six forced fumbles and 21 interceptions. Arguably his best season was 2008, during which he made 72 stops and intercepted seven passes.
The Packers struggled mightily in the secondary in 2011, due in part to Collins' absence. They allowed a league-high 4,796 passing yards, the highest total ever surrendered in NFL history.
It is unclear if Collins' injury will preclude him from making a return to the field somewhere other than Green Bay.