Just some interesting insight about Gore's 46-yard run that was penalized with the 15-yard horse collar tackle. From Mlive's Justin Rogers: http://www.mlive.com/lions/index.ssf/2011/10/a_second_look_sf_third_quarter.html
10:51 -- 2nd-and-13 at the San Francisco 17
After Frank Gore's 46-yard run in the first quarter, the back was held in check until this play. Like on his previous big run, the 49ers used Delanie Walker in the H-back role and had him set a wham block on defensive tackle Ndamukong Suh, but unlike the previous run, Cliff Avril collapsed inside instead of rushing the edge, closing the lane Gore used to break free in the first quarter.[...]
To add insult to injury, cornerback Chris Houston was flagged for a horse-collar tackle on Gore, a 15-yard infraction. After chasing down the running back, Houston did grab Gore's jersey in between the shoulder pads, but didn't yank him to the turf by it. The official should have used judgement on intent on this play.
In all, the play with the penalty yards tacked on went for 69 yards.
We certainly blew many chances to win, but more of the blame should be on our offense. This big play really wasn't the fault of our defense.