An exhilarating, game-winning drive that put the San Francisco 49ers in position to seize the top seed in the playoffs next week would normally be reason to celebrate.The mood for the 49ers was far from joyous following a 34-31 victory because teammates were more concerned about the well-being of third-string quarterback C.J. Beathard, whose younger brother Clayton was fatally stabbed earlier in the day at a Nashville bar.