A year ago, the 49ers were a brick wall for opposing running backs. Not only was there nowhere to run, a large number of ball carriers -- Felix Jones, Montario Hardesty, Jahvid Best, Pierre Thomas, to name a few -- had to be helped off the field and never returned.
This year? The wall has crumbled a bit. Running backs in three of the last four games have broken 100 yards, a sacred barrier a year ago that only one tailback, Seattle's Marshawn Lynch, achieved. Lynch's 100-yard game also had an asterisk. He did it in a game that linebacker Patrick Willis missed with a hamstring injury.
A year ago, teams averaged 77.3 yards a game on the ground against San Francisco. That was easily the best yards-against average in the league. This year, it's 95.3 yards a game, which is still good for seventh overall, but nearly 20 yards a game more than last year. The 49ers already have allowed three rushing touchdowns, the same number they gave up in 18 contests last year.
In 2011, opponents gave up on running against the 49ers. That wasn't the case Sunday. Steven Jackson carried the ball 29 times alone as the Rams held the ball nearly seven minutes more than the 49ers. The last time Jackson has carried the ball more than 29 times: Dec. 28, 2008.
He finished with 101 yards Sunday, so his average was still rather pedestrian -- 3.5 yards a carry. Still, one of the factors in his success was that his offensive linemen were constantly breaking through to the second level of the 49ers defense where they could take on linebackers Willis and NaVorro Bowman. Bowman finished with a game-high 13 stops, but many were several yards downfield. He had one tackle behind the line of scrimmage.
Meanwhile, the 49ers on Monday face a Chicago team that ranks ninth overall in rushing and likely will be without starting quarterback Jay Cutler.
-- Matt Barrows