Even though the Giants traded for former No. 9 overall pick Keith Rivers from the Bengals the week before they re-signed Chase Blackburn, it appears that Blackburn is a starter now and Rivers is not. They don’t play the same position technically, although Rivers could be used inside in training camp as a backup to two spots. He also would play behind WLB Michael Boley, whom GM Jerry Reese hinted could be moved inside. Boley says he believes he is the weak-side linebacker going forward, and it appears that Blackburn, the late-season hero who came off his couch to start for the Giants’ Super Bowl-winning defense, remains in line to play a lot of snaps again. Health obviously will be a factor, but Rivers could earn a role as a sub-package linebacker. Observers say that Rivers has looked good so far, but that the Giants’ LB depth is quite strong, which could limit the bench players’ possible reps.