The Bears' defense, which finished No. 5 last season in yards allowed, could be missing a lot of key parts by the time NFL training camp begins in July.
Strongside linebacker Nick Roach, who missed just three games over the past five seasons and started 59 times, is now an Oakland Raider.
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The 27-year-old, six-year veteran agreed to terms with the Raiders Friday morning after visiting the previous day. In addition to becoming a fixture on the strong side, Roach started the final four games last season at middle linebacker after Brian Urlacher suffered a torn hamstring.
Roach was sixth on the Bears with 84 tackles in 2012, when he started 14 games, missing two starts only because the Bears opened in a nickel alignment with an extra defensive back. He was originally signed by the San Diego Chargers in 2007 as an undrafted free agent out of Northwestern and placed on their practice squad, but was signed to the Bears' active roster late that season.
Roach also started three times at middle linebacker in 2009 when Urlacher missed 15 games with a dislocated wrist. That season, Roach finished tied for the team lead with 10 tackles for loss.
With Urlacher also free to sign with another team, the Bears could be left with very little at the position behind seven-time Pro Bowl weakside linebacker Lance Briggs. The only other linebackers on the roster are primarily special-teams players Blake Costanzo, J.T. Thomas and Dom DeCicco. Costanzo has started one NFL game, while the others have never started.
In addition to Urlacher, defensive lineman Israel Idonije, who has missed one game in six years and started 42 games the past three seasons, is also an unrestricted free agent.
Another unrestricted free agent, guard Lance Louis, who was the Bears' best offensive lineman last season, visited the Dolphins Thursday night.
But the Bears have few dollars left under the $123 million salary cap after signing former Saints offensive left tackle Jermon Bushrod and ex-Giants tight end Martellus Bennett.
"We are up against the cap," general manager Phil Emery said. "So we are going to have to be very slow and methodical and make sure that every decision that we make is going to be in the best interest of our team moving forward in terms of putting the best players on the field to win."
Friday afternoon the Bears found enough spare change to re-sign one of their own unrestricted free agents, backup cornerback Zack Bowman, who was also one of their top special teams coverage men in 2012. The 6-foot-1, 196-pound Bowman provides depth behind starting corners Charles Tillman and Tim Jennings.
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