Isaac Sopoaga had been with the San Francisco 49ers continuously since 2004, when Dennis Erickson was head coach.Around the NFC West: March 13, 2013Alex Smith (2005) and Delanie Walker (2006) came to the team during Mike Nolan's tenure.All three left the 49ers shortly after the 2013 free-agent signing period opened Tuesday.Another San Francisco mainstay, Dashon Goldson, was visiting with the Tampa Bay Buccaneers and all but certain to join Sopoaga, Smith and Walker as former longtime 49ers.