A revamped special-teams unit in San Francisco has gotten stronger.

The 49ers are re-signing special-teams ace Blake Costanzo, his agent David Canter said Tuesday. Costanzo was with the 49ers in 2011, and then left in 2012 for Chicago. The 49ers' special teams unit dipped when he departed.

The 49ers recommitted to special teams last season when they brought in Bubba Ventrone and Kassim Osgood. Costanzo, a fan favorite in San Francisco, only strengthens the 49ers’ special teams. He played for 49ers special-teams coach Brad Seely in Cleveland.

Costanzo plays inside linebacker and gives that unit depth as NaVorro Bowman recovers from a torn ACL. The 49ers have yet to announce the deal. They must make a corresponding move because they are at the 90-man limit.