SANTA CLARA, Calif. -- The San Francisco 49ers aren't giving away any playbook secrets when they say their top priority in Sunday's NFC championship game at Seattle is to protect the ball.CenturyLink Field is by far the loudest stadium in the NFL. It has been a nightmare for opposing teams -- including the 49ers who have been outscored by a combined 71-16 in their last two games there -- to operate offensively.The result is often turnovers.