RENTON — When the Seahawks traveled to San Francisco for their season opener, the question about the 49ers was just how much they’d struggle in 2011.

The 49ers, after all, were coming off of a very disappointing six-win season, one that cost Mike Singletary his job. And while newly hired head coach Jim Harbaugh had overseen an impressive turnaround at Stanford, he had yet to prove himself at the NFL level, and making things even more challenging, the 49ers were coming into the season behind the curve with a new coaching staff thanks to the NFL lockout.

Now, 14 games later, the only question about the 49ers, who are 11-3, is just how far they can go in the playoffs.

In a remarkable one-year turnaround, San Francisco has gone from a team with a losing record to one that still has a chance at a first-round bye. Thanks to the early season struggles of the rest of the teams in the division, the 49ers were the first team in the NFL to clinch a division title. What’s even more impressive is that the 49ers have drastically altered their fortunes without making huge changes to the roster. There’s no new stud quarterback or dynamic playmaker to point to as the clear difference maker.

So how in the world have the 49ers gotten so good after looking like such a mess a year earlier?

“It’s pretty simple,” defensive end Justin Smith said on a conference call. “We’ve won some games we didn’t win in the past. We’ve been able to close out some of those tight games and hold on to leads that we haven’t been able to in the past. It’s just the little things that add up to big ones.”

Certainly a lot of the credit for San Francisco’s improvement goes to Harbaugh, a coach known for his attention to detail and intense coaching style.

“Just his mentality, the way he prepares us, our practice habits and everything you do is a reflection of your head coach in one way or the other,” Smith said. “He’s just a no-nonsense, football guy and I think it’s done wonders for this team.”

As Smith said, the 49ers are closing out close games, something they didn’t do last season, which makes it hard not to wonder what might have happened had Seattle completed its comeback in the season opener. After trailing by 16 points at halftime, the Seahawks cut the lead to two points late in the fourth quarter, only to see their comeback hopes slip away thanks to two return touchdowns by Tedd Ginn Jr. Had the 49ers opened their season by blowing that big lead, would they only be one game worse in the standings, or might that have altered the team’s entire season? That’s an impossible question to answer, but certainly that season-opening win helped set the tone.

“Any time you start the season opener and you drop one that hurts,” Smith said. “It chips away at your psyche a little bit and what your team is trying to accomplish. Definitely for us, when they came down here and we got the win against a division opponent, that helped put us on the right path.”

Smith, who Harbaugh calls his team’s MVP, is a big part of a defense that has given up the fewest points and rushing yards in the NFL this season. San Francisco has forced 32 turnovers, the second most in the league, and perhaps most impressively, has not given up a rushing touchdown this season.

And if the 49ers winning formula of playing solid defense, winning the turnover battle and running the ball sounds familiar, well, it should. Pete Carroll wants his team to play the same way, and over the past six games, five of which have been wins, the Seahawks are winning in a very similar fashion to the 49ers.

“It’s a classic way of putting together a football team and I think Jim has done a great job of selling it and getting it done,” Carroll said. “… The formula has been very similar. We’re very similar as we go into this game in what we’re trying to accomplish every time we go out.”

Herald Writer John Boyle: jboyle@heraldnet.com. For more Seahawks coverage, check out the Seahawks blog at heraldnet.com/seahawksblog