Before the 2012 season began, I wrote that the San Francisco 49ers would struggle to repeat last season’s greatness and that they would regress from their 13-3 record from the 2011 campaign. Five days from now, the San Francisco 49ers are going to play in Super Bowl XLVII. Both those statements are true, so it’s safe to say that the Niners outplayed my expectations this year. That’s fine; football is the toughest game to predict, and I’m always going to get some things wrong.

What I’m interested in figuring out is why the Niners succeeded. If I had statistical evidence from before the season suggesting that there was a high probability the 49ers would take a step backward this year, why didn’t they? The numbers aren’t perfect, but is there some number that specifically stands out as being flawed? What does that tell us about teams like the 2012 and 2013 49ers going forward? And, most importantly for the terms of this weekend, how has this year’s Niners team changed from my (and other analysts’) preseason conceptions into the team that will run onto the field in New Orleans Sunday evening?

Let’s start with my preseason expectations. After writing that column on the likely regression awaiting the 49ers, I noted in the sidebar of Simmons’s NFL season preview that the 49ers would go 9-7 and win the NFC West by one game over the Seahawks. That’s not horribly off, considering that the 49ers finished 11-4-1 and won the NFC West by a half-game over the Seahawks. And in terms of the “R-word,” the 49ers did regress: They declined by 1.5 games from their 13-3 record of the previous season. It’s also very clear that they were a better team — occasionally much better — than the one I expected to see during the season. Going to the Super Bowl confirms that, but I don’t feel like this 49ers team is really all that much better than last year’s team, who would have made it to the Super Bowl themselves if it weren’t for some bad luck with fumbles in the NFC Championship Game. Had Harry Douglas stayed upright last week to catch Matt Ryan’s pass, the Niners might very well have lost this year’s NFC Championship Game, but it wouldn’t really change the impetus to do this column.

Looking back, I mentioned six statistical indicators or qualitative ideas as arguments in favor of the idea that the Niners would regress. How do those look after the year played itself out? Let’s see. From the top down:

1. The 49ers improved by seven wins from 2010 to 2011, and teams who improve by six to eight wins in a given year almost always decline the following season. Twenty-five of the 32 teams fitting that criterion declined the following year, losing an average of 3.2 additional games the following year. The Niners did decline under those terms, but only by 1.5 games (counting the tie as a half-win).

2. The league-leading plus-28 turnover differential that fueled the 2011 team isn’t sustainable. This one was entirely accurate: History suggested that the 49ers would lose an average of 20 turnovers and takeaways from their league-leading margin, and they actually lost 19; the 49ers had a turnover differential of plus-nine this year, dropping San Francisco back to the pack at eighth. After intercepting a flukishly high 18 passes in 2011, the four starters in the San Francisco secondary picked off only six passes this season, with the likes of Carlos Rogers coming back to earth. And after maintaining a ridiculous 1.1 percent interception rate last season, Alex Smith’s interception rate more than doubled to 2.3 percent during his nine games as the starting quarterback. Colin Kaepernick kept his rate at 1.4 percent, but in all, the 49ers finished with an interception rate of 1.8 percent this year. They also fumbled more frequently and recovered a lower percentage of their fumbles. Teams with that sort of decline in turnover differential saw their win-loss record decline by an average of 2.5 games, so within range of the 1.5-win drop produced by the 49ers.

3. Randy Moss and Mario Manningham aren’t real upgrades for the offense because they don’t fit into the conservative Alex Smith scheme. Moss and Manningham hardly produced big numbers this season, as Moss was an ancillary figure while Manningham struggled with injuries. They would have fit better in a full season with Kaepernick at the helm, but it’s hard to say that the offense directly improved because of the additions of Moss and Manningham.

4. The defense won’t be able to stay as healthy as they have been. Nope, that one’s a loser. San Francisco’s 11 defensive starters missed a total of four games this season, which is even more impressive than their performance from a year ago. We’ve seen how the injury to Justin Smith has slowed the San Francisco pass rush, so it’s not unreasonable to think that they would decline if an essential player went down with an injury, but they’ve simply managed to stay healthy for another season.

Is this merely the status quo for the 49ers on defense? Possibly. The 49ers ranked third or better in defensive Adjusted Games Lost (AGL, an injury statistic I created during my time at Football Outsiders) three times in four years from 2008 through 2011, and they’ll likely be in the top three again this year. I found some anecdotal evidence in the past that teams who play a 3-4 alignment tend to remain healthier than defenses who suit up in a 4-3, a virtue that might have something to do with the additional bulk often employed in a 3-4, but no 3-4 defense in recent memory has been as healthy as these 49ers defenses have over the past several years. I don’t know that one team’s health is enough for me to write off the idea that health from year to year is random, but it’s enough to make me hesitant in projecting an eventual regression to the mean for the 49ers here. (The Wyatt Earp Effect might also very well explain how the 49ers are so notably healthy.)

5. The 49ers were 6-2 in games decided by one touchdown or less in 2011, an unsustainable level of performance in close games. San Francisco didn’t sustain that level of clutch performance; they made it through without playing many close games at all. The 49ers were 2-1-1 in games decided by one score or less this season.

6. Their schedule will be tougher. This turned out to be very accurate, as the 49ers played the league’s easiest schedule in 2011, per DVOA, and the league’s third-hardest schedule in 2012, per the same metric. Pro-Football-Reference.com has the Niners with the sixth-easiest schedule in 2011 and the third-hardest schedule in 2012. Going from an easy schedule to a tough one almost always induces a notable decline, but the 49ers only really suffered a minor dropoff in terms of their win-loss record.

So, in all, most of the things historical trends saw coming for this year’s Niners actually came true, but for whatever reason the 49ers were able to roll with the punches and decline by only 1.5 wins from the previous year’s total. The only number I really wish I’d paid more heed to in hindsight was San Francisco’s point differential from the 2011 season, which suggested that they had the Pythagorean record of a 12.3-win team. A huge gap between a team’s win-loss record and expected win-loss record from their point differential is still the best indicator of future changes in their winning percentage (see: the 2011-12 Minnesota Vikings), and the 49ers’ point differential suggested a much milder decline than some of the other factors I mentioned.

Of course, the numbers also can’t tell the entire story of a team, and there were some things that stood out about this year’s Niners that both the numbers and my intuition didn’t grasp. Let’s start with the really obvious one:

1. Colin Kaepernick became the starting quarterback. Obviously, the midseason shift to Kaepernick has become the defining moment of San Francisco’s campaign, and even the biggest 49ers fan couldn’t have predicted that Kaepernick would be this good this soon. His ability to lead quick drives downfield has been a weapon the 49ers simply didn’t have last year. Does Alex Smith beat the Saints in a shootout in New Orleans? Or the Patriots in a game where Justin Smith gets hurt and the defense collapses in the second half in Foxborough? Would he have been able to lead a comeback from down 17-0 against the Falcons in Atlanta? It’s hard to say. The 49ers were 6-2 with Smith as the starter and 5-2 with Kaepernick as the starter (with a 16th game being the Rams contest in which Kaepernick came in for an injured Smith), but Kaepernick played a tougher schedule. The offense had also begun to sputter with Smith at the helm, as the 49ers had scored just 40 points in Smith’s three final games before the Rams start that saw him get that infamous concussion. I wrote at the end of my piece before the season that “49ers fans dreaming of a Super Bowl run might want to dream about life with a real quarterback instead.” As it turns out, they’ll get to dream — and see — both.

2. The running game was ridiculously good with Smith under center. Before Kaepernick took over in the second quarter of Week 10, the 49ers moved the ball with a running game that had turned from average and mundane during the previous year to dynamic and wildly successful in 2012. Through their first eight games of the 2012 season, the 49ers averaged an incredible 5.6 yards per pop, which is the fourth-best figure for any team since the AFL-NFL merger in 1970. Not bad! Part of that was a rejuvenated Frank Gore, but the 49ers also got help from an unlikely source

3. San Francisco can’t help themselves from turning backups into superstars. In 2011, the find was NaVorro Bowman, who turned the 49ers defense on its ear with his dominant play alongside Patrick Willis. This year, it’s been two players: Kaepernick at quarterback and Alex Boone at guard. You’ve seen what Kaepernick can do, but Boone has been an underrated star as a mammoth mauler at guard. If San Francisco is really as good at identifying, drafting, and then developing players with midround grades or worse, well, it’s going to be hard to ding them for losing a starter or two when they can bring in the next set of Harbaugh trainees.

4. Aldon Smith actually improved. With his increased run responsibilities and the natural regression for guys with Smith’s sort of sack total in their rookie season, it was easy to point out that he would likely see his pass-rushing totals drop during a difficult sophomore one. Instead, Smith took his game to new heights, producing 19.5 sacks and making the All-Pro team. He’s struggled some since Justin Smith suffered his triceps injury, but Smith is arguably the best pass rusher in the NFC already.

5. Jim Harbaugh remained an incredible upgrade. At the bottom of my initial piece, I brought up the examples of Bill Belichick and Sean Payton as coaches who had a breakout season at the beginning of their careers before returning to right around .500 the following season. It can be a huge upgrade to add an elite coach, but that tends to have the most impact during your first winning season. Harbaugh has been every bit the coach he was last year during this current campaign, and while I’ve said more than once that swapping out Mike Singletary for Harbaugh was the biggest coaching upgrade a team has ever made, even that statement might not be enough to point out just how much the 49ers gained from making that switch.

In all, I think it’s less that the Niners defied the odds and more that they changed their style of play and scheme. The 2011 49ers were a conservative, ball-control team that relied upon their defense to force turnovers and produce excellent field position for their limited offense. They waited for the other team to make mistakes and then exploited them. This year’s 49ers team is more aggressive on offense, perhaps owing to their quarterback change. They’re more conservative on defense because they don’t get as many turnovers as they did a year ago, so they’re instead built around coming up with stops on third down (where they rank as or among the league leaders, depending on how the stat in question is split out) and a heavy pass rush from Aldon Smith. And last year, when the offense stalled, the 49ers would turn the ball to David Akers for yet another successful field goal. This year, while Andy Lee has kept up his brilliant punting, Akers has lost his touch and had a dismal campaign, costing the Niners a league-leading 17.8 points of field position. I don’t think last year’s 49ers team — had they remained with the same roster and the same schemes — would have been able to win 11 games this season. On the other hand, I suspect that these 49ers — the ones with Kaepernick under center — will win 11 games in 2013. They might even get a head start on that total by winning this Sunday.