They ground out a 13-8 victory on the road against a rookie quarterback, Andy Dalton.
They won what turned into a 36-32 postseason shootout against the NFL's hottest quarterback, Drew Brees.
They came back from 20 points down in the second half to beat Philadelphia on the road. They ran away from previously 3-1 Tampa Bay to win a blowout, 48-3.
With the 49ers sitting one victory away from the Super Bowl, I went through their games looking for threads tying together their victories and defeats this season.
Turnovers are generally key for any team; the 49ers led the league in differential. But as the game against Detroit demonstrated, the 49ers could beat a good team on the road without prevailing in that pivotal category. That was one of six games this season the 49ers won after trailing in fourth quarters.
A few things jumped out over the course of the season, counting playoffs:
The 49ers gave up 20 sacks in their three defeats. That included nine at Baltimore, six against Dallas and five at Arizona. They allowed 28 sacks in their 14 victories.
Attacking the 49ers' pass defense is key. The 49ers' record was 0-2 when allowing more than 8.5 yards per pass attempt and 2-3 when allowing more than 6.6. They were 12-0 when allowing less than that. The 49ers were also 9-0 when collecting at least three sacks. They were 1-2 when opponents completed better than 65 percent of their pass attempts. The Giants' Eli Manning completed 65 percent. The 49ers batted down his final pass to help preserve their 27-20 victory.
The chart ranks opposing quarterbacks by yards per play when dropping back to pass or scrambling. The quarterbacks ranking near the top generally defeated the 49ers or made them sweat out victories. Dallas connected on long pass plays late to beat San Francisco. Arizona had pass plays for 60, 53 and 46 yards during its victory over the 49ers. The chart shows only regular-season opponents, but the Saints' Drew Brees nearly beat the 49ers with 66- and 44-yard touchdown passes.
Attacking the 49ers' run defense seems less critical. The 49ers were 12-0 when allowing more than 2.6 yards per rushing attempt. They were 2-3 when allowing less than that. Yes, you read that correctly. They even went 3-1 when allowing 25 or more rushing attempts. They were 11-1 when allowing more than 55 yards rushing, including 4-0 when they allowed more than 92.
The 49ers were 3-2 when allowing more than 20 points, including 2-1 when they allowed 27 or more. They were 4-0 when allowing more than 20 first downs and 9-1 when allowing more than 16 of them. They were 10-1 when opponents ran at least 60 plays and 4-2 in the other games.
Venue matters. Alex Smith has 15 touchdowns passes, three interceptions and 17 sacks in nine home games. He has five touchdown passes, two interceptions and 31 sacks in eight home games.
Vernon Davis matters. Davis has 67 receptions for 884 yards and eight touchdowns in the 49ers' 14 victories. He has seven receptions for 88 yards and no touchdowns in three defeats. He averages 2.1 times as many receptions for 2.2 times as many yards in the 49ers' victories.
2011 49ers Opponents: Yards/called pass
Those are a few variables I noticed. There are quite a few others, surely. Which ones matter most in your view?