Smith went 18-of-24 for 303 yards, three touchdowns and no interceptions, leading the 49ers to a 45-3 drubbing of the Bills. Included in that was a quarterback rating of 156.2, which is just 2.1 points off from a perfect passer rating game (158.3).
Since then however, Alex Smith has struggled while the 49ers have gone 1-1. Against the New York Giants in Week 6, Smith was a mess. He went 19-for-30 for 200 yards and three interceptions with no touchdowns. His quarterback rating was 43.1, which is closer to a passer rating you get if every pass you throw falls incomplete (39.6) than the 156.2 he posted the week before.
Smith and the 49ers did manage to rally back in Week 7 with a win against the Seahawks on Thursday Night Football, but it's not like he improved. Smith was 14-of-23 for 140 yards, one touchdown and one interception with a passer rating of 74.5.
This isn't a terrible game (although he did make some terrible throws), but it wasn't great either. It also didn't win the game for the 49ers.
The 49ers have Frank Gore and the defense to thank for their Thursday night victory. Gore rushed for 136 yards on 16 carries, while their defense held Seattle to six points and only 251 total yards.
Those two factors aren't only what won the 49ers the game on Thursday, but are why they are currently 5-2.
It's not a newsflash to anyone that San Francisco's defense is among the best in the league. The 49ers rank first in the NFL in yards allowed per game, and third in points allowed per game.
San Francisco's running game has been solid all season, averaging 176.6 yards per game, good for first in the NFL. The 49ers pass offense hasn't been anywhere near as prolific, averaging 216 yards per game. That puts them at 24th in the NFL.
Smith hasn't exactly been the turnover machine he was in years past, but his four interceptions and three fumbles aren't exactly shining endorsements of his abilities either. Granted all four of those interceptions came in the last two weeks, but it is a troubling trend.
While Smith was lauded for not throwing any picks in his first five games, the 49ers did limit his pass attempts to an average of 27 per game. It's also interesting to note that in both of the 49ers' losses, Smith threw the ball 30 times or more, while in four of their five wins, he threw the ball fewer than 30 times.
The 49ers are one of the best teams in the NFL, but it's still the defense and the running game that make them an elite team, not their quarterback.