Going by the percentages, the 49ers should not even be here.

Going by the percentages, they should be watching football this weekend on television. They should not be on the field Sunday at Bank of America stadium, facing the Carolina Panthers in the second round of the NFL playoffs.

Last February, you may recall, the 49ers lost the Super Bowl. Historically, losers of Super Bowl games tend to fall off a cliff the following season.

The statistics are telling. Thirty one of the previous 47 Super Bowl losers -- two out of every three -- have either failed to get back to the playoffs the following season, or have lost their first playoff game when they did return. And all of the last 18 Super Bowl losers -- or 100 percent of them -- have failed to get back to the big game the next season.

San Francisco 49ers’ Michael Crabtree (15) runs after a catch against the Green Bay Packers in the first quarter at Lambeau Field in their NFC
San Francisco 49ers' Michael Crabtree (15) runs after a catch against the Green Bay Packers in the first quarter at Lambeau Field in their NFC wild-card game in Green Bay, Wis., on Sunday, Jan. 5, 2014. (Nhat V. Meyer/Bay Area News Group) ( Nhat V. Meyer )

Finally, the most daunting mountain: It has been 40 years since a team that lost the Super Bowl returned to win the next one -- the 1972 Miami Dolphins.

Yet here are the 49ers, making a real run at that achievement.

Vic Fangio, the team's defensive coordinator, has an incisive theory about why that has happened.

"Yeah, I do," Fangio said. "We've got good players. And I'd like to think they're well coached, too."

It's never quite that simple, of course. But the 49ers have clearly avoided the dreaded "Super Bowl Hangover" effect that causes so many teams to become either (A) frustrated and depressed or (B) overconfident and complacent after nearly reaching the summit.

Dan Skuta, a linebacker and special teams man, was wondering about the same stuff last spring when he came to the 49ers as a free agent after spending his previous four seasons in Cincinnati.

"When I signed, one of my thoughts was, 'I hope these guys are still hungry,' " Skuta said. "But I was here for just one day and could tell they were. You would have thought they had gone 0-16 from the way they were working out and preparing."

San Francisco 49ers’ Tramaine Brock (26), Ray McDonald (91) and  Eric Reid (35) tackle Green Bay Packers’ Eddie Lacy (27) in the first quarter
San Francisco 49ers' Tramaine Brock (26), Ray McDonald (91) and Eric Reid (35) tackle Green Bay Packers' Eddie Lacy (27) in the first quarter at Lambeau Field in their NFC wild-card game in Green Bay, Wis., on Sunday, Jan. 5, 2014. (Nhat V. Meyer/Bay Area News Group) ( Nhat V. Meyer )

The 49ers may indeed buck the odds by getting back to the Super Bowl. But to do so, they must endure a preposterous gantlet. They will have to win three consecutive road games in three time zones with temperatures ranging from minus-13 wind chill in Wisconsin to sunny 55 degrees in North Carolina.

It sounds impossible. It might be impossible. But the 49ers are already one-third of the way there.

It's easy to forget now, but there was a time back in September when the dreaded post-Super-Bowl hangover seemed to be taking effect. But after losing in consecutive weeks to Seattle and Indianapolis, the 49ers went on a five-game winning streak and righted the ship.

How did that happen? Some players credit coach Jim Harbaugh, who made certain that when the offense was struggling and the defense was dominant, defensive players didn't start pointing fingers across the locker room. Harbaugh made sure that all mistakes on both sides of the line resulted in accountability.

"When things like that happen, he brings it up and puts it right up there," Skuta said. "He doesn't let it go unmentioned and simmer. I like that. Why not talk about it and try to use it for the good?"

NaVorro Bowman, the linebacker having a breakout season, credits the front office bringing back most of the key players from 2012, plus the overall team mind-set.

"I just think the guys on this team are used to winning," Bowman said. "They want to win. They do everything to win. And sometimes it doesn't work out that way. But that doesn't mean we're going to deter our play because we lost. We're going to keep doing things that help our team. I think that's what got us back here."

For teams trying to make a Super Bowl encore, there are other issues. For one, they're coming off a shortened offseason, having played longer than all but one other team in the league. There are often contract issues in retaining star players and distractions from players receiving more publicity. Plus, every Super Bowl team -- win or lose -- goes into the next season as a target, the game circled on the schedule by every opponent.

San Francisco 49ers’ running back Frank Gore (21) runs with the ball while being tackled by Green Bay Packers’ Brad Jones (59) in the fourth
San Francisco 49ers' running back Frank Gore (21) runs with the ball while being tackled by Green Bay Packers' Brad Jones (59) in the fourth quarter of their NFC wild-card playoff game at Lambeau Field in Green Bay, Wis., on Sunday, Jan. 5, 2014. San Francisco defeated Green Bay 23-20. (Jose Carlos Fajardo/Bay Area News Group) ( JOSE CARLOS FAJARDO )

The combination of factors can be lethal. When the Raiders lost the Super Bowl after a great 2002 season, the franchise practically imploded and hasn't been back to the playoffs since.

The 49ers, meanwhile, have done just the opposite of imploding, if there is such a thing. They don't appear surprised in the least to be in their current position, having overcome some tough odds to face even more tough odds.

"It seems like the mind-set around here goes that way," punter Andy Lee said. "I feel like, a lot of us feel, that we're just as good or better a team than we were last year."

Going by the percentages, the 49ers' season should be finished by now. But percentages never take a team to the Super Bowl or keep a team away from one, as the 49ers are in the process of reminding us. Sunday, the percentages better be ready for another beating.

Contact Mark Purdy at mpurdy@mercurynews.com. Follow him at Twitter.com/MercPurdy.