Michael Crabtree doesn't do exhibition games. Mike Singletary specializes in crisis management. And the Monterey Peninsula is a wonderfully misty place to run the "nutcracker" drill.

Who knew the 49ers could discover so many little-known facts about themselves in a single preseason month?

With little ground left uncovered, the 49ers tucked the exhibition season to bed with Thursday's final practice run, a 17-14 victory over the Chargers at Candlestick Park. They went 4-0 for the first time since 1992.

Don't get too excited. Nineteen of the 37 teams to do that since 1990 didn't make the playoffs.

"I'm glad the preseason is over," Singletary said.

With the season-opener at Seattle nine days away, here is what the 49ers learned about themselves that matters most this preseason:

-- Quarterback Alex Smith knows what he is doing, and when's the last time that's been the case?

The answer is college, the last time he went consecutive years with the same offensive coordinator and offense - until now, Year 6 of his NFL career.

Smith knows the audibles and protections. He recognizes defenses and potential problems. Smith is so comfortable, and the 49ers are so comfortable with him, that he got the exhibition finale off as a healthy scratch for the first time in his career.

Now, whether he can do something with all this knowledge is another story. That won't be told until the games start. If he can't, David Carr - 5-for-6 for 58 yards in Thursday's start - is on deck, with Nate Davis decidedly in the hole.

-- Ready or not, two rookies will make the offensive line better.

The two first-round picks - right tackle Anthony Davis and left guard Mike Iupati - have much to learn about starting in the NFL. But their accelerated learning path and tremendous upside has the 49ers' offense in better hands.

Iupati has instantly become running back Frank Gore's new best friend, able to scooter his wide body to the second level and deliver devastating blocks.

Against the Chargers, Iupati cleared space downfield for running back Anthony Dixon to take a pitch left, cut inside and take off for a 46-yard touchdown run in the first quarter.

Davis has a steeper curve to negotiate. But, at age 20, he won't do any worse than former starter Adam Snyder and already looks noticeably better than he did when camp started.

Davis, too, created room for Dixon to cut right three times in his score.

-- The special-teams unit has finally gotten past the point of no return.

The 49ers were among the NFL worst in both return categories last season, when touchbacks and fair catches served as best-case scenarios.

Ted Ginn Jr. is a wind-burning touchdown waiting to happen. If rookie Kyle Williams doesn't routinely average 10 yards per punt return, rookie Phillip Adams might.

Adams scored a touchdown last week and followed up with a 26-yard punt return against the Chargers.

The blocking has been there. The 49ers now have returners with the instincts to hit the hole and the burners to come out the other side.

Other than that, the 49ers merely confirmed their long-established suspicions. Inside linebacker Patrick Willis is still a playmaking beast. The natural pass rush, and by extension the pass defense, is still a concern. And, no one runs a seam route like Vernon Davis.

Vernon Davis explains: Davis said he was keeping Crabtree "in check" when he confronted him during Wednesday's walk-through. The heated argument lasted more than 20 minutes before Singletary helped settle the matter.

"Just keeping his head level and just getting on him about some things he did in the past," Davis said without elaborating. "It was a matter of being a team captain. All I was doing was taking care of my responsibilities.

"I hope he got the message. I think he did."

Crabtree did not talk with reporters after sitting out an eighth career exhibition game. "Anything I see that I feel is wrong or that I need to address, then I'm going to say something," Davis said.