Blake Costanzo, the charismatic special-teams standout who became both a fan- and locker-room favorite in 2011, is back with the team after agreeing to a one-year deal.

Costanzo left for Chicago as a free agent early in 2012, and the 49ers’ special-teams coverage units dipped that season. They rebounded last year with a core group of players that included Ray “Bubba” Ventrone, Kassim Osgood and C.J. Spillman.
The 49ers released guard Al Netter, a member of their practice squad the past two years, to make room for Costanzo on the 90-man roster.

Costanzo, 30, played for 49ers special-teams coordinator Brad Seely in Cleveland before joining him in San Francisco in 2011. He quickly emerged as the leader of the so-called “Tony Montana squad,” the nickname given to the fun-loving and full-of-swagger coverage units

Costanzo ended that season as the team’s top special-teams player, leading the 49ers in solo tackles (10) and knockdowns (27). He also led the Bears in special-teams tackles last year. Chicago made no attempt to re-sign him this offseason.

Costanzo also plays inside linebacker, which already has the best competition of the offseason. Michael Wilhoite, Nick Moody, rookies Chris Borland and Shayne Skov, and now Costanzo, will compete to fill in for NaVorro Bowman while he recovers from an ACL tear. Costanzo will wear No. 56.