Linebacker had been one of the deepest positions on the Bears' roster in training camp, but the decision to place Hunter Hillenmeyer on injured reserve after Week One took a key reserve out of the mix for the rest of the season.

Hillenmeyer, who had been the primary backup to MLB Brian Urlacher, is dealing with the effects of a concussion he suffered in Chicago's third preseason game. The eighth-year veteran had suffered at least one concussion earlier in his career, and he did not travel with the Bears to the final preseason game. The team said he had been cleared to play in Week One but had to leave the game after becoming ill.

Some have speculated that the Bears would have handled the situation differently had Hillenmeyer not been the team's union representative, but the NFL is becoming much more careful about how to proceed with players who have suffered concussions, given the effects such an injury can have on the brain. GM Jerry Angelo said he consulted with doctors and felt he took the best approach.

"(Hillenmeyer is) just a guy you're really going to miss," a clearly disappointed Bears DT Tommie Harris said Sept. 15 in the locker room at the Bears' practice facility. "He's one of the smartest players I've ever been around, so I hope he comes back and recovers well."

There's a combination of concern and optimism when it comes to the linebackers remaining on the roster.

Nick Roach, the top backup at strong-side linebacker, is being hampered by a hamstring injury and he's been injury-prone throughout his career, so the Bears have been forced to investigate the free-agent market and consider trade options. They signed LB Rod Wilson, who belonged to the Bears from 2005-07, to add depth and help out on special teams after Hillenmeyer was placed on I.R., but observers say he doesn't completely fill the void.

Depth could be an issue for the rest of the season, but the good news for the Bears is that their starting linebackers have looked better in the early going than some had expected. Urlacher and WLB Lance Briggs shined in the season opener, and any concerns about Urlacher wearing down have been put to rest for the moment. The Bears are confident that Pisa Tinoisamoa can be a playmaker on the strong side.