Kurtenbach: Cancel the coronation — the 49ers’ embarrassing loss to Baltimore is a gut-check that will make or break the San Francisco’s season

SANTA CLARA — If you’re a 49ers fan who received Super Bowl tickets for Christmas, you might want to ask for a gift receipt.

That’s because the showdown between the AFC and NFC’s top seeds, the Ravens and Niners — the biggest game of the regular season — didn’t turn out to be much of a contest.

Brock Purdy threw four interceptions, the 49ers’ defense was carved up like a holiday roast by Ravens quarterback Lamar Jackson, and the Niners were blown out 33-19 at home in front of a national television audience.

This was too big a game to chalk up as unimportant or uninformative. Bad luck or injuries had nothing to do with the loss.

“We got our tails kicked in,” George Kittle said.

And that’s the first time that’s really happened to the Niners this season without an obvious excuse.

Yes, San Francisco went up against a worthy adversary and didn’t look worthy of the stage.

That’s the kind of loss that throws everything into question for San Francisco.

This is the kind of moment that can make or break a team’s season.

And what the Niners do next will define their season.

Yes, the Niners must re-earn their reputation as a Super Bowl favorite after Monday.

This team will show us in the next two weeks if it is the genuine article.

If they aren’t, we’ll find out just as fast.

Here’s the good news: The Ravens might have whooped the Niners, but they have a well-established record of doing that to teams in their opposite conference.

Jackson is now 20-1 against the NFC in his career.

It makes sense: There’s simply no way to recreate the one-of-one quarterback in practice, so if it’s a one-off to face him on the field, he always has the upper hand.

Oh, and the fastest feet of any quarterback in NFL history, too.

Jackson made things even tougher for the 49ers’ defense by, according to Nick Bosa, changing the way he’s played this season for Monday’s game.

“Throughout the year on tape, he was kind of sitting in the pocket and going through his reads in the pocket,” Bosa said. “Tonight, I think he was looking for that escape lane quicker and then finding guys down the field.”

Bosa called it “super impressive.”

We know, Nick, we saw the game. Jackson might have won himself the MVP on Monday.

Now, the lessons Jackson taught the Niners’ defense don’t really apply anywhere else. No quarterback in the NFC playoff picture can do what he does. He’s the only one in the AFC, too.

This might have been a one-off.

(The Niners would be happy to reassess this in February.)

Along the same lines, there’s no one else in the NFL that plays defense as aggressively as the Ravens.

Baltimore puts seven or eight players on the line of scrimmage. It’s not a surprise that they did it against the 49ers, but the disguise of stunts, blitzes, and coverages did prove too much for San Francisco.

That dynamic defensive front left the Niners’ offensive line flustered and Purdy under constant siege.

So, instead of diagnosing the defense at the line of scrimmage and delivering the ball to the right spot after the ball was snapped, Purdy had to read the defense after the snap. With little time to throw, he made multiple bad decisions.

One other team in the NFL resembles the Ravens’ defense: the blitz-crazy Vikings. Don’t forget that the Niners lost to them, too, with Purdy throwing two critical late-game interceptions.

But for 30 other NFL teams, being that aggressive on defense is a recipe for disaster. They don’t have the athletes to confuse an offense like the Niners’ or a quarterback like Purdy — to play this way would be asking to be shredded for 450 yards. We’ve seen it happen repeatedly this Niners season.

All that said, don’t ignore the blueprint the Ravens drew up Monday.

The Niners’ future opponents certainly won’t.

Going into Monday’s game, the Niners’ path to the Super Bowl could have been considered more a coronation than a challenge.

Every bit of available data said that the Niners were a juggernaut — heads and shoulders above the competition. They have an all-time great offense and top-tier defense. They didn’t seem to need special teams — their field-goal kicker made his first 3-pointer since mid-November Monday.

The Ravens might not play in the Niners’ conference, but they skewed that data.

And San Francisco doesn’t look so tall now, do they?

The Niners might have been home for Christmas, but after Monday, this team is now one loss in the final two weeks from possibly hitting the road in the NFC Playoffs.

And that’s just a big-picture issue.

The game also provided concerning injuries to Trent Williams and his backup at left tackle, and perhaps a crisis of confidence for the man at the helm of the offense.

Monday was Purdy’s first four-interception game as a professional. He didn’t have a four-interception game in 48 collegiate contests at Iowa State, either.

And his takeaway after a four-giveaway game was downright existential:

“I gotta ask myself, ‘Who are you?'” Purdy said. “It’s easy to be riding the high and thinking you’re the man when things are going well, winning games… you don’t see a whole lot of adversity.

I have to look myself in the mirror.”

And he said he needs to be willing to take the check-downs instead of always looking for the deep play.

“It’s easier to [push the ball downfield] when you don’t have that many turnovers going on,” Purdy said. “That’s where I think I have to grow.”

The quarterback might not be in the running for MVP anymore — there’s no coming back from an embarrassment like that on national television this late in the season — but with the Niners’ title hopes still intact and tied to the quarterback, his comments are telling and concerning.

They’re also a reminder that Purdy has only started 23 NFL games and is only 23 years old.

The Niners’ Super Bowl hopes rest on a quarterback who has been incredible (before Monday) but is still green. The Ravens made that undeniably clear.

Niners coach Kyle Shanahan is not green, however.

The Niners made things slightly interesting in garbage time Monday, but the fact remains that a Shanahan-coached team has come back from an eight-points-or-greater fourth-quarter deficit in Shanahan’s tenure as head coach.

The margin, of course, was much larger than eight in the fourth quarter against Baltimore.

They’re now 0-37 in such games.

This team might be a front-runner.

And whether you think that’s true or not, the Niners better get back in front.

The first chance to do that is Sunday in Landover, Maryland. No cross-country trip to a 10 a.m. Pacific time game is easy, but the Washington Commanders’ defense should help right the Niners’ ship.

Following that is a Week 18 showdown with the red-hot Rams. A game that, after Monday’s loss, is guaranteed to have meaning.

It will now be anything but straightforward for the Niners to reach Las Vegas and Super Bowl LVIII.

In a way, the playoffs have effectively started for this team.

This could bring out their best or continue their worst.

Let’s see if this team is the genuine article.