Linebacker Derek Smith re-signed with the San Francisco 49ers on Monday, passing on the possibility of free-agent riches to sign a three-year deal with the teams he has led in tackles for five straight seasons. Though not one of the NFL's best known linebackers, Smith has been one of the league's most productive for nearly a decade. He has been the 49ers' defensive leader since signing before the 2001 season as a free agent from Washington, where he was the Redskins' leading tackler in each of his four seasons.