SAN FRANCISCO -- I know what you’re thinking, San Francisco 49ers fans.

You’ll take your team’s 13-6 victory over the Seattle Seahawks at Candlestick Park on Thursday night. You're thrilled Frank Gore ran all over the Seahawks' second-ranked rush defense. You loved watching Seattle's receivers and tight ends drop passes all over the Candlestick turf. But you’re worried about the quarterback.

You’ve seen enough from Alex Smith over the past two weeks -- the four picks, the pre-2011 indecisiveness -- to affirm what you secretly feared all along. Smith’s progress under coach Jim Harbaugh was a carefully orchestrated mirage, a product of superior coaching, a strong ground game and a punishing defense.

The old feelings about Smith surfaced during that three-pick defeat to the New York Giants last week. They washed over you in waves Thursday night when Smith ran around and threw that killer pick to Seahawks cornerback Brandon Browner in the red zone.

The championship optimism that pervaded your thinking only a couple weeks ago has vanished into the Candlestick night. You're having a tough time envisioning how the 49ers will reach that next step, the Super Bowl, with this relapsed No. 11 behind center.

You might be right in the end. Smith’s recent play is concerning, for sure. But the 49ers won an NFC West slugfest against a formidable opponent, and that should be enough for right now. The victories can't all be pretty. The other quarterback, Russell Wilson, completed 9 of 23 passes, none in the third quarter.

"That is the NFL -- it's the ups and downs," Smith said after the 49ers took over first place in the NFC West with a 5-2 record. "You’ve got to be able to ride them out."

That will be much easier for the 49ers if their offensive line is going to open running lanes the way it did Thursday night. The Seahawks can feel the same way. Both teams produced 100-yard rushers against defenses that almost never allow them.

Gore went for 131 yards on 16 carries, charging into the Seattle secondary time and again. Marshawn Lynch carried Seattle with 103 yards on 19 rushes, running over defenders as though they were traffic cones on the freeway. It's tough to fault 49ers safety Dashon Goldson for going after Lynch and drawing a penalty. He couldn't let another man run over him along the sideline, as Lynch had done, without firing back.

Neither team is going to face defenses as tough as these outside the NFC West.

"We've got one of those divisions that is a defensive-driven division right now," said Seahawks cornerback Richard Sherman, who stared down Tom Brady a week ago and won. "A lot of the defenses are playing well. It's just a battle right now. Every game with every team is a heavyweight bout."

None of these heavyweights are winning on points.

"It wasn't going to be pretty," Smith said. "It wasn't going to be a stat game. It was going to be do-whatever-it-takes. Turn on both of our games from last year and it was like this."

Seattle has scored only 35 points in its three NFC West games -- all defeats, all on the road. But the Seahawks' divisional opponents have managed only 52 points against them, 17.3 per game. Seattle's seven-point margin of defeat against San Francisco was the widest yet for the Seahawks in any of their losses.

The St. Louis Rams have 36 points in two division games. The Arizona Cardinals have 23 in two. The 49ers have 13 in their lone NFC West game.

Smith wasn't pretty Thursday night. There will be a right time to evaluate quarterback play in the bigger picture. That time is not now. Not after a game like this.

"Really, within the building, the locker room, you can’t have the drastic ups and downs," Smith said. "You guys like to write about them and make a big deal about it, but really you’ve got to move on to the next opponent and get ready.

"You break records [621 yards against Buffalo] and then last week it wasn’t good at all offensively. Today, we ran the ball really well. It wasn’t pretty necessarily in the pass game but we got it done."

The pick Smith threw from the Seattle 7-yard line begs for some explanation. The 49ers faced third-and-goal. They led 10-6 and had to get points, even if it meant settling for a field goal.

Smith rolled left and spotted Randy Moss in the back of the end zone. The play had departed from its script, however, and defenders lurked in places where Smith couldn't immediately find them.

"We had a zone coverage there and he tried to squeeze one in there and I happened to be in the right place at the right time," Browner said.

Harbaugh rode to his quarterback's rescue, as usual. He kept a straight face while saying Smith was "fantastic for us all night." He suggested Smith had played a perfect game at the line of scrimmage, and the results in the run game back up that contention. Smith has the authority to make run checks at the line. His decision making very likely helped the 49ers find weaknesses in a previously impenetrable defense.

That won't undo the interception, of course.

"Randy is running in the back of the end zone, Browner is occupied with Frank or Kendall (Hunter) on that play in the front corner," Smith recounted. "He steps into it and you're not seeing everything."

Smith's four interceptions over the past two games are only one short of his total for the 2011 season. The 49ers' downfield passing game had been gaining momentum until last week. In retrospect, the 49ers might have drifted just a bit from their established identity as a power running team. They got back to basics against Seattle, largely abandoning the Wildcat looks and other oddities that appear creative in victory and gimmicky in defeat.

Gore had gotten zero second-half carries in the 26-3 loss to the Giants last week.

"We always try to pound the ball with Frank," 49ers tight end Delanie Walker said. "Sometimes we go away from it in different games, but when it's a tough game like this one, we try to get Frank the ball because he's great at finding holes."

The 49ers have 11 days to recover and self-scout before facing the Cardinals in a Monday night game at University of Phoenix Stadium. Arizona hasn't allowed more than 21 points in a game this season. The nation might see another NFC West slugfest. The goal, then as now, will be to get out alive.

The big-picture stuff can wait.