SANTA CLARA, Calif. (AP) -- When Alex Smith is good he can be very good. When Smith is very good, the San Francisco 49ers are practically unbeatable.
While the staples of San Francisco's success this season remain a rock-solid defense and the NFL's top-ranked rushing game, Smith's play at quarterback has been a key variable that's put the 49ers over the top in a string of lopsided victories.
The first-place 49ers begin the second half of the season Sunday against the St. Louis Rams at 6-2 with a 112-game lead in the NFC West. The six victories have come by an average margin of 20 points, and Smith has a 120.0 quarterback rating in those games.
The eighth-year veteran is coming off one of the best performances of his career as the 49ers return from their bye week, but Smith knows his strong season to this point will ultimately be judged by what he and the 49ers do the remainder of the year.
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