The San Francisco 49ers are bringing back one of their key special teamers.According to a league source, Kassim Osgood has agreed to terms on a one-year deal.Osgood, who will turn 34 in May, was a big reason why the 49ers coverage units improved so greatly in 2013. The 49ers ranked 31st in the NFL in kick coverage in 2012 and allowed a kick return for a touchdown in their narrow Super Bowl loss to Baltimore. Osgood, long known as one of the best special teamers in the NFL, was brought in and it paid instant dividends.