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 a star for the 49ers' special teams in 2011. He left in 2012 for Chicago. The 49ers' special teams unit dipped when he departed.The 49ers re-committed to special teams last season when they brought in Bubba Ventrone and Kassim Osgood. Costanzo, a fan favorite in San Francisco, only strenghens the 49ers' specila teams.