SANTA CLARA, Calif. -- The San Francisco 49ers defense has been playing at a high level most of the season. It's been dominant the past two weeks and they team has gotten back on the winning track.A key to the high level of play has been venerable defensive lineman Justin Smith. 49ers' coach Jim Harbaugh said Wednesday that Smith got a game ball for his efforts against the St. Louis Rams just like he did the previous week against the Washington Redskins.