Geno Smith’s eyes reddened.

Tariq Woolen was crying. So was Cody Barton, something the 26-year-old middle linebacker, one of the sport’s toughest positions, said he’d never done after a football game.

The Seahawks’ locker room, a place of so much fun and youthful exuberance this unexpected playoff season, knew it was all over.

When for more than half this playoff game against the mighty San Francisco 49ers, it was theirs.

It started as one of the biggest surprises in Seahawks postseason history. They had the lead at halftime at mighty San Francisco. Coach Pete Carroll was running his Air Monarchs off the field at the break, his right fist in the air.

Then, what has doomed the Seahawks from surprising fall into uneven winter doomed their season.

Game-turning turnovers. Crushing, inexplicable penalties. And a defense that can’t stop anyone when it must.

A crushing and baffling penalty for left guard Damien Lewis being illegally downfield on a quick hitch-route pass created the situation the Seahawks had avoided all Saturday, the spot in which Seattle failed against the 49ers in all three meetings this season.

Smith’s ensuing sack and lost fumble on third and long late in the third quarter was the point when the 49ers turned a tense, one-score game into their runaway, 41-17 victory in an NFC wild-card playoff game at wet Levi’s Stadium.

“This game was there to be had for us,” Smith said.

“In so many ways, we can be so much better. And that starts with me…

“I’m not at all satisfied. I’m going to take this personally.”

The final score suggested the Niners smashed the Seahawks en route to their 11th straight victory and a place in the divisional round.

Eventually, they did, outscoring Seattle 27-6 after halftime, and out-gaining them 505 to 332 yards.

“They whipped our ass. They could do whatever they wanted,” lineman Quinton Jefferson said, speaking for his entire Seahawks defense this game and most of this season.

”It was a frustrating game.”

But on offense the Seahawks truly smashed themselves, to end a surprising season and 10th playoff appearance in 13 seasons at 9-9.

Now the Seahawks must decide whether to draft a quarterback or the desperately needed run stopper and defensive linemen and linebackers who can make a difference with the four picks they have in the first two round of this spring’s draft. That includes the fifth-overall choice, from Denver in the trade of Russell Wilson.

They also must decide how much to offer Smith in a new contract, and for how long. His one-year deal ended with this loss.

“I want to finish my career in Seattle,” the 32-year-old quarterback said after his season of going from a seven-year NFL backup to Pro Bowl selection, Seahawks record-breaker and first career playoff start.

“I want to be here. The town, the city, the team, Coach Carroll, the organization, they all embraced me. I was a guy who probably could have been out of the league. They embraced me.

“I want to re-pay them for that.”

Carroll said “I hope so” when asked if he wants Smith to return.

Seattle was driving inside the San Francisco 25-yard line down 23-17 late in the third quarter. That was after Smith completed a dart of a pass to DK Metcalf for 13 yards on third and 12..

On second and 9, a 7-yard yard pass from Smith (25 for 35, 253 yards passing, two touchdowns, one interception) to Tyler Lockett would have had Seattle at the 12 and poised to take the lead with a touchdown. But that gain got wiped out because the line officials spotted left guard Damien Lewis illegally downfield as an ineligible receiver, inexplicable for an interior offensive lineman on an quick option hitch route.

“You know, it varies with the referee crews,” Smith said. “Some will call it. Some won’t.

“We can’t complain about it. ...

“Like I said, it was a different crew, maybe they don’t call it.”

Officials are supposed to give offensive lineman a 2-yard cushion past the line of scrimmage on a pass before they consider him illegally down the field. Smith threw the ball so quickly, it was hard to see Lewis more than 2 yards down the field moving his 327 pounds that quickly.

“Very questionable call,” Lockett said, after he and other Seahawks looked at the video of the play in the locker room after the game.

“Very, very tough, because I think Geno threw it in 1.2 seconds. So it’s hard for anybody to get past the line of scrimmage in that time.”

Instead of third and 2 at the 7-yard line, Seattle had third and 14. That’s when San Francisco’s pass rush is lethal, where Seattle spent most of their two regular-season losses to the 49ers.

The charging 49ers got to Smith, almost on cue. Defensive end Charles Omenihu smacked into Smith and the ball as the quarterback looked to throw. All-Pro Nick Bosa recovered Smith’s fumble at the Niners 30.

Instead of getting within a field goal at 23-20, the Seahawks stayed down 23-17.

The 49ers could then unleash Christian McCaffrey (119 yards on 15 carries) and their running game, with the lead and the clock in their favor.

Lewis took the high road for the key penalty call on him.

“Oh, man, it’s just something to learn, and move on from it and look to the future,” Lewis said. “I can’t say nothing to the ref. The ref, he can do what he wants to do.

“He can move on, and look to the future.”

A 32-yard pass from Brock Purdy to Deebo Samuel behind Seahawks Pro Bowl cornerback Tariq Woolen set up Purdy’s 7-yard touchdown pass to running back Elijah Mitchell on a scramble play. The two-point conversion pass put San Francisco up 31-17 with 14 minutes left.

The 11-point swing was like third and longs are against the 49ers’ defense: Deadly. Season-ending.

Incredibly, Lewis was called for being illegally downfield on passes three times in the second half. That’s more than guards should be called for that in a season.

An interception Smith threw trying to connect with Lockett, Smith’s ninth turnover the last eight games after four in his first 10, set up another 49ers touchdown. And the rout was on.

Smith to Metcalf startles 49ers

Just as with his season replacing traded Russell Wilson as Seattle’s starter, Smith started nearly perfectly — but faded badly at the end.

On third and 3 midway through the second quarter, Smith noticed the 49ers in a rare blitz. He saw Metcalf outside left one on one with Charvarius Ward, San Francisco’s best cover man. Metcalf ran by Ward. Seattle’s offensive line gave Smith the time to wait for Metcalf to run by him. His pass to Metcalf was in stride and onto his hands for a 50-yard touchdown.

Despite an awful start and 10-0 deficit, the Seahawks suddenly led 14-13.

The 49ers answered with a field goal with 17 seconds left in the half to re-take the lead. And that looked like it would be the halftime score. But on Seattle’s lone offensive play on the ensuing mini-drive, San Francisco nickel defensive back Jimmie Ward hit Smith near the head after the quarterback had given himself and a scramble run up with a slide.

The 15-yard penalty NFL officials always call on such a play pushed the ball across midfield and gave Jason Myers a chance at a 56-yard field goal. The Pro Bowl kicker had been making them from 60 yards to that stadium north end before the game. He drilled this one, too.

Coach Pete Carroll ran to the locker room in his Air Monarchs with his right fist in the air. And the buoyed Seahawks took a stunning, 17-16 lead into halftime.

Levi’s Stadium sounded like Levi’s Library.

The Seahawks’ locker room was rockin’.

“Oh, we were lit, man. We were ready to come back out and fight some more,” safety Ryan Neal said.

“We just couldn’t finish it. We couldn’t finish the job.

“(But) at that point, I think people were like, ‘Oh, God! This is about to go down.’

“We’ve just got to finish the job. That’s it.”

At that point, Smith was 9 for 10 passing for 104 yards and a passer rating of 143.3 just before a perfect 158.3.

He then missed on five of his next 13 throws with two turnovers in the second half.

Metcalf finished with 136 yards on 10 catches with two touchdowns. The second score was 3 yards in garbage time, with 1:48 left. That closed the scoring at 41-23.

Going at Tariq Woolen

Teams have learned trying to beat Woolen on deep passes with his 4.26-second speed in the 40-yard dash is a bad idea.

So San Francisco coach and play caller Kyle Shanahan went at the rookie Pro Bowl cornerback across the field, rather than down it.

By late in the second quarter, Purdy had thrown four times at Woolen. That was more times than most teams did entire games in the regular season. The Niners kept succeeding on long-developing crossing routes versus Woolen, because Purdy kept getting time to throw them in stride to laterally running receivers.

The Seahawks knew they needed to run Kenneth Walker effectively into San Francisco’s top-ranked defense to make Smith’s play-action passes more effective with shorter third downs than Seattle’s first two games against the 49ers this season. On defense, wet and sloppy field or dry, the Seahawks had to stop McCaffrey and Elijah Mitchell from running.

Rushing defense was Seattle’s weakest area during the regular season. The 49ers ran for 189 and 170 yards against the Seahawks in San Francisco’s 27-7 win in week two at Levi’s Stadium and 21-13 victory at Lumen Field last month. And those romps came when the 49ers had Mitchell out injured and, in September, had yet to trade for McCaffrey midseason from Carolina.

Early in the third quarter, on a third and 7 at the Seahawks 37, Shanahan had Purdy target Woolen on yet another crosser, with Deebo Samuel. Linebacker Cody Barton ran into the trailing Woolen trying to tackle Samuel, and the Niners receiver ran all the way to the Seattle 16 for another conversion on Woolen.

Then, on the first play of the fourth quarter, Aiyuk got behind Woolen and Purdy found him for a 32-yard gain, to the Seattle 7. That was the first vertical route completed on Woolen in the game.

The 49ers’ took complete control with a 38-17 lead and 11 minutes left in the game after Aiyuk blocked Woolen for about 10 seconds down the field. That allowed Samuel to catch a pass alone in front of Woolen then run past him getting blocked for a 74-yard touchdown.

Woolen sat on the bench after that score, his shoulders slumped as teammates Tre Brown and fellow rookie Coby Bryant talked to him.

Pro Bowl safety Quandre Diggs said all the deep, long crossers was Shanahan’s preparation beating Seattle’s excecution.

“That’s just part of guys attacking certain coverages and certain things,” Diggs said. “He drew up some great things. They did some things that they normally didn’t do.

“But for us, we’ve got to be better in all aspects of the game. And today, we weren’t.”

Again.

Suboptimal start

All week, Smith and the Seahawks offense talked of needing shorter third downs this time against San Francisco to have a chance for drives and points, unlike the long yardage in the first two meetings.

Seattle had third and 2 on each of its first two drives Saturday.

The first time, Smith held onto the ball watching Metcalf and Lockett run into three 49ers defenders at the line of scrimmage. With no one open, he took a 10-yard sack, by Arik Amstead.

The second drive, Smith kept the ball on a read-option fake hand-off, around left end. He got dumped for a 2-yard loss.

Two third and 2s, minus-11 yards, two three-and-out drives and punts.

Presto! The Seahawks trailed 10-0 midway through the first quarter.

That was because McCaffrey ran 68 yards cutting inside way-overrunning Bruce Irvin outside. That set up Purdy’s third-look, 3-yard touchdown pass. McCaffrey broke outside to the right flat late uncovered, after pass blocking initially on second down.

Seahawks outside linebacker Uchenna Nwosu threw up his hands in frustration at the bust on McCaffrey touchdown.

But the Seahawks answered with a 14-play drive that ended with an equal number of touchdowns the Seahawks’ offense had in two full games against the 49ers in the regular season. Seattle closed to within 10-7.

Poona Ford saves 4 points

Defensive tackle Poona Ford is the Seahawk with the highest salary-cap charge this season, above $10 million. For much of the season he didn’t produce up to that status.

He did midway through the second quarter Saturday.

The 49ers were driving into the red zone threatening to go back up by two scores in a 10-7 game. On first down, Ford ran through his blocker and forced McCaffrey to run inside him into teammates for a 1-yard gain. On second down, Ford against burst through the line and into the backfield to force Purdy out of the pocket — and into teammate Bruce Irvin for an 8-yard sack.

On third and 17, Shanahan chose a white-flag run by McCaffrey and settled for the consolation field goal by Robbie Gould.

Ford’s two plays kept it a one-score game, with Seattle trailing only 13-7.

Smith threw his go-ahead touchdown pass to Metcalf a few plays later.