The Bengals linebackers have been among the worst in the NFL for a couple years now. The room needs a productive veteran leader. Trevathan fits that bill. The former Bronco and current Bear is a Super Bowl champion who plays with his head on a swivel and is always around the ball.
Since entering the league in 2012, he has three 100+ tackle seasons. The soon to be 30 year old does have a somewhat lengthy injury history. This may drag him more into the Bengals price range. This franchise never breaks the bank for anyone.