He won 13 straight games to start the season with the New Orleans Saints two years ago. Then they dropped their final three before going on to capture the franchise’s lone Super Bowl title.

“We lost the last three games going into the playoffs, so that kind of calmed everything down a little bit,” said Goodwin, the 49ers’ first-year center in his 10th NFL season.

That’s why Goodwin guards against getting overly excited about the current seven-game winning streak by San Francisco (8-1) — even with a commanding five-game lead in the NFC West and Arizona coming to town having lost four straight in the series. The Cardinals (3-6) managed only 13 total points over the previous two meetings.

“It definitely feels good to be winning, but there are still seven games left before the postseason even starts,” Goodwin said. “In this league, you can’t get ahead of yourself.”

The Saints realized early in 2009 it could be a special season. The 49ers sure hoped that would be the case for them this year despite the lockout slowing that process after San Francisco hired coach Jim Harbaugh away from nearby Stanford.

Yet nobody could have envisioned the Niners being nearly this good — as in one 27-24 overtime loss to Dallas in Week 2 from being unbeaten.

Whether he says it or not, Harbaugh has changed the culture for this franchise and brought back memories of

the dynasty days and those five Super Bowl rings won in the 1980s and ’90s.

“I don’t think you create an identity. I think you become it,” Harbaugh said. “You become what you are. You become your identity. From my standpoint, being around these guys, this team, these coaches, it’s the team, the team, the team. It’s about the team.”

It has been that way for this group since well before the season opener back on Sept. 11 against Seattle. That was the last time the streaking 49ers were tested by a divisional opponent, and they whipped the Seahawks 33-17 in Harbaugh’s NFL debut. The Niners haven’t slowed down since.

From quarterback Alex Smith’s poise in the pocket and heady decision-making to the key contributions of newcomers Goodwin, cornerback Carlos Rogers and kicker David Akers, San Francisco is on a roll like nothing this organization has experienced in 14 years.

“They’re an impressive football team,” Cardinals coach Ken Whisenhunt said. “Kudos to Alex. I think they’re a very talented bunch and they’re well coached. Coach Harbaugh’s done a great job with those guys.”

Now, the Niners look to clinch the division — and their first playoff berth since 2002 — as soon as possible considering both Arizona and Seattle are 3-6 and St. Louis 2-7.

Not that this game is a gimme.

“This is not a trap game for us. This is a rivalry game,” left tackle Joe Staley said. “We expect the best effort out of them. It’s always a very physical game regardless of records. We came into their place when they went to the Super Bowl that year, went to their house and beat them. We had a bad record that year.”

The Cardinals have to be a little more confident coming to Candlestick Park this time after snapping an 11-game road losing streak against the Eagles last week — a team the 49ers also came from behind to beat 24-23 in Philly on Oct. 2.

John Skelton, playing for injured starting quarterback Kevin Kolb the past two weeks, connected with Early Doucet on a 5-yard touchdown pass with 1:53 left in the Cardinals’ 21-17 victory.

“You have to have that sense of urgency, and I think as an offense we really do that,” Skelton said. “We turn it up a notch in the fourth quarter.”

Kolb is nursing an injured right foot that might keep him out again. Skelton knows there will be some tense moments Sunday against a talented Niners team and top defense.

“It’s intense. It’s probably as good as any in football,” he said. “They are 8-1. We’ve got two wins recently, so we are kind of on the upswing, too. We know it’s going to be a physical and intense game, and we just have to minimize the mistakes and be successful that way.”

Larry Fitzgerald is coming off a two-touchdown game for an Arizona team that has suddenly won two straight on the heels of a six-game skid after not getting back-to-back victories all of last season. Four of Fitzgerald’s five TDs have come in road games.

“I’ve played Larry a couple of times,” said Rogers, who has five interceptions in his first season with San Francisco after spending his first six years with Washington. “It’s been a good matchup. We know how Larry is, a great receiver. One of the best. Deep-ball guy. I don’t think his speed is like that, but he can get open any time. That’s going to be a great matchup again.”

The Cardinals can’t afford mistakes against these 49ers, like Jay Feely’s first-quarter missed field goals from 35 and 43 yards last week.

San Francisco’s defense stopped Giants quarterback Eli Manning in the waning moments of a 27-20 victory last Sunday. Justin Smith batted down a pass on fourth down from the 10 to seal it. Those kinds of plays didn’t go the 49ers’ way in recent years, when they regularly were on the other end of late-game heartbreakers.

Alex Smith has now led four fourth-quarter comebacks, three during a 4-0 road start.

“It’s one of those things where we understand what we have to do,” linebacker Parys Haralson said. “I think as far as the defense and the team, it’s a team with a lot of fight. We don’t give up, man. We know that it’s a 60-minute football game.”

Two San Francisco stars sat out the final meeting last season against Arizona. Pro Bowl inside linebacker Patrick Willis didn’t start for the first time in his career after undergoing a second surgery on his broken right hand. Running back Frank Gore was sidelined for his fifth straight game to end the season after fracturing his right hip.

Gore’s status is in question for this week because of a right ankle injury.

Personnel aside, the 49ers are prepared to treat this game as one of equal magnitude to last week’s showdown with the Giants — and that much-anticipated Harbaugh vs. Harbaugh Thanksgiving affair next Thursday when the 49ers face Harbaugh’s big brother, John, and the Baltimore Ravens.

“They play us hard,” tight end Vernon Davis said of the Cardinals. “They match our intensity. We can’t take them lightly. We have to go out and attack them right away.”

By sundown Sunday, the 49ers and Raiders will officially be halfway done with their regular seasons. In past years at this point, they would also be realistically done with their seasons. Because they were both so dreadful.

Begone, dread. To the delight of Northern California football citizens, both teams are very much in the playoff picture. Let us pause, then, to salute both teams for surprising us with their unexpected pre-November achievements and glory.

OK. Pause over.

The truth is, even though the 49ers and Raiders seem to be in good shape, their seasons could still go either way.

Yes, the 49ers are currently on a downhill ride to a division title. But too much hubris or (especially) a key injury might send them sideways. Yes, the Raiders are in a winnable division and possess the only quarterback on either Bay Area team who has started a playoff game. But a few ill-timed penalty flags (a Raider tradition) could ruin the master plan.

There is no better time to outline the best-case and worst-case scenarios for both teams, broken down by the most important factors.

Quarterbacks

Best-case scenario: Alex Smith keeps managing games well for the 49ers as he keeps gaining confidence. Carson Palmer is everything the Raiders hoped he would be and by December is rekindling memories of his 2005 season in Cincinnati when he led the NFL in touchdown passes.

Worst-case

scenario: Smith gets injured and the 49ers must rely on rookie Colin Kaepernick, who loses the last four games. Palmer’s troublesome throwing elbow keeps bothering him, and he can’t make the hard downfield deliveries, leading to underthrown interceptions and defeats.

Defenses

Best-case scenario: Patrick Willis and NaVorro Bowman continue to devour opposing tacklers for the 49ers. In Oakland, Richard Seymour uses his championship pedigree with the Patriots and spearheads a Raiders goal-line stand that helps beat the Chargers next Thursday night.

Worst-case scenario: One of the dynamic linebacking duo gets hurt and is out for the season, throwing off the schematic symmetry and allowing opponents to exploit tight end matchups over and over. The Raiders pass defense continues to be shaky (it’s 25th in the league), and the Chargers carve up the Silver and Black secondary in both their meetings.

Coaching

Best-case scenario: Jim Harbaugh keeps Freddie P. Soft at bay, and the 49ers keep believing nobody has it better than them. Hue Jackson’s decision to acquire Palmer looks golden as he hooks up with old pal T.J. Houshmandzadeh on crucial third-down possession plays (which you know they will import from the Bengals’ former playbook) over and over.

Worst-case scenario: Harbaugh gets suspended for the rest of the season after inciting a postgame wrestling match with his brother after beating Baltimore, and the leaderless 49ers collapse. Jackson’s swagger falls flat on its face when he tries one too many trick plays and inexcusably loses to the Chicago Bears, causing the Black Hole fans to form an “Occupy Hue” protest movement that pitches tents in the offensive meeting room.

Divisional races

Best-case scenario: The 49ers take advantage of the rotten NFC West competition by clinching the NFC West title with a rout of St. Louis on Dec. 4, then use a strong finishing kick to earn a first-week playoff bye. The Raiders sweep their remaining four division games, then hold on to win the AFC West as they watch nothing-special Kansas City and always-haunted San Diego self-destruct.

Worst-case scenario: There honestly might not be an absolute worst case for the 49ers, who could probably clinch the division title by winning just two more games and finishing with a 8-8 record. The Raiders’ nightmare, though, would be a loss next Thursday at San Diego and then physically punishing defeats at Green Bay and at home against Detroit, which would leave those last two games against Kansas City and San Diego as must-wins.

Won-loss records

Best-case scenario: After a Sunday victory over the Redskins, the 49ers go on to sweep their remaining five divisional games and pick off the New York Giants at home to finish 13-3 and earn a bye week in the playoffs. The Raiders roll over Denver at the Coliseum and win four more before losing to the Packers, then finish with three more victories and conclude a stunning 12-4 season.

Worst-case scenario: Battered by injuries, the 49ers struggle to defeat anyone except St. Louis and Seattle, going 9-7 before an early playoff exit. And the Raiders, as the Carson Palmer experiment implodes, beat only Denver and Miami to go 6-10 and put Jackson’s job in jeopardy.

The ultimate best-case scenario, of course, would be a Raiders vs. 49ers matchup in the Super Bowl. Only a nut case would predict that sort of best case. But ponder this very amazing thought: Both teams reaching the Super Bowl this season is probably more likely than the ultimate worst case, which is both teams failing to make the playoffs.

In other words, we’re definitely not in 2009 any more. Thank goodness.

Contact Mark Purdy at mpurdy@mercurynews.com or 408-920-5092.

When the 49ers pushed longtime analyst Gary Plummer out of the radio booth, I was among those to worry that Plummer’s blunt assessments would be replaced by someone who would stamp a smiley face on even the worst defeat.

Here’s a new blunt assessment: I was dead wrong.

Eric Davis exploded the notion that he is anybody’s house organ last Sunday by blistering the 49ers during a 27-24 loss to the Dallas Cowboys. This is what Davis said on the 49ers radio network after quarterback Tony Romo connected with Jesse Holley for the pivotal 77-yard pass in overtime:

“Oh, my goodness. I don’t know how you could be in the secondary and not know that was coming. They ran play-action, and everyone on the left side of the defense for the San Francisco 49ers in the secondary bit on the run fake. That’s ridiculous. You have to know that they’re going to try to throw the ball up top. … That was horrible, horrible.

“There’s no other way to put it: That was a bad play by the secondary that led to a defeat. … There’s no way whatsoever that Jesse Holley should have been that butt-naked running through the secondary in that situation.”

No spoonful of sugar there — not even a speck.

Davis, in an interview later in the week, laughed off the idea that his new job would require him to bite his tongue. “That’s not in my nature,” he said. The two-time Pro Bowl cornerback said that, from the start, no one from the 49ers has given the

slightest hint that there would be restrictions on what he can say or how he can say it.

Still, because he was replacing the famously candid Plummer, Davis was aware that “a lot of people were under the assumption that I was going to say that all things 49ers are all good and it’s a perfect organization.

“No. The fact is … I have more integrity than to get out there and try to be a homer and lie to the fans.”

Plummer spent 12 years in the 49ers radio booth before being let go in the offseason with a year remaining on his contract. The 49ers never explained their decision, but the website Deadspin.com provided a plausible explanation when it unearthed an X-rated interview Plummer had done on KSJO-FM in February.

Plummer told this paper that he was fired after refusing repeated requests to tone down his criticism of the 49ers during broadcasts. He called the racy interview “a convenient excuse to get rid of somebody who told the truth.”

Davis said no one from the 49ers mentioned the need for a more positive vibe during his hiring process. Just to make sure, Davis broached the topic himself.

“What I did talk to them about was the ability to let me do the job and to be who I am,” he said. “Of course everyone knows I get paid by the 49ers. I’m a former 49er, and I’m a Niners fan. But my job is to analyze the game. … If it’s a bad play, I’m going to say it’s a bad play.”

Davis, who spent 13 seasons in the NFL (including 1990-95 with the 49ers), has also shown a Plummer-esque knack for using his expertise as a former player to anticipate game situations. When returner Ted Ginn was tackled for a loss on a risky punt return against Seattle, Davis defended Ginn’s approach by saying “there are times when he might be wrong, but he’s going to make a big play.” (Ginn went on to return a kickoff 102 yards and a punt 55 yards, both for touchdowns.)

In Week 2, just before the Cowboys’ big play, Davis observed that the defensive backs should be on high alert because the ball was likely headed their direction. And when the 49ers got burned, Davis saw no need to douse the fire.

“I’m not going to call a bear a cat,” he explained. “If there’s a grizzly on the field and I’m saying, ‘kitty, kitty, kitty,’ the fans are going to see right through that.”