SEATTLE -- At the far end of an otherwise quiet postgame locker room, veteran defensive tackle Shelby Harris answered questions in his typically gregarious manner, seemingly unfazed by the Seattle Seahawks’ most disappointing loss of the season.

“Discouraging? We play in the NFL,” said Harris, who had one of Seattle’s only stops of Josh Jacobs on a record-setting day for the Las Vegas Raiders’ running back in their 40-34 overtime win over the Seahawks. “If you get discouraged off of that, you might as well throw your pads in and give up on the season. … It’s about the adjustments you make, week in and week out. That’s what makes this team this team.”

The Seahawks are back in the all-too-familiar position of having to turn their struggling defense around. They did it earlier this season after another miserable start on that side of the ball. Whatever adjustments they have to make this time must happen in a hurry, lest they lose any more ground to the San Francisco 49ers, who are hitting their stride right as Seattle’s defense is skidding.

The 49ers’ fourth consecutive win on Sunday coupled with the Seahawks’ second straight loss gives San Francisco a one-game lead in the NFC West standings. They have a win in hand over Seattle and will come to Lumen Field for a Thursday night rematch in Week 15. According to ESPN’s Football Power Index, the Seahawks now have a 64.3% chance of making the playoffs (down from 68.2% last week) but only a 7.9% chance of winning the division (down from 14.8%).

“Reality is that we're going from the hunter to the hunted,” quarterback Geno Smith said. “People want to play us. As a young team, we've got to learn to be able to go out there and win those games. That's our next step in the evolution as a really young team. We got to understand the moment, capture the moments, take advantage. I feel like we had plenty of opportunities to go out there and win that game, finish it late, and we just didn't get it done.”

The playoffs will be a moot point unless the Seahawks can fix a defense that has regressed to its early-season form, particularly against the run. They allowed 161 rushing yards in their loss to the Tampa Bay Buccaneers in Munich before last week’s bye. That was partly a function of a game plan that underestimated Tampa Bay’s ineffective running game, focused instead on stopping Tom Brady, but didn’t do either.

The game plan was again part of the problem against the Raiders. Coach Pete Carroll said all the attention the Seahawks paid to All-Pro receiver Davante Adams (seven catches for 75 yards) was a factor in Jacobs going off, but that alone hardly explains why Jacobs gashed Seattle to the tune of 229 rushing yards, the most they’ve ever allowed to a single player. That topped the previous record of 221 rushing yards that Bo Jackson had against the Seahawks in 1987.

The indelible image of that performance was Jackson sprinting down the sideline for a 91-yard touchdown run before disappearing into the Kingdome tunnel. Jacobs did his best Bo impression by shooting through a big hole in the middle of Seattle’s defense and racing to the end zone for a walk-off 86-yard touchdown run in overtime, a fitting end to a game in which Las Vegas won the line-of-scrimmage battle on both sides of the ball and continually ran it down Seattle’s throat.

Jacobs added 74 receiving yards as the Raiders compiled 576 as a team, the third-most against the Seahawks in franchise history.

“We didn’t tackle him as well as we needed to and we didn’t scheme him as well as we needed to,” Carroll said.

With their pass rush also going cold -- a combined five QB hits and just one sack over the last two games -- the Seahawks’ defensive issues have reduced the margin for error for Smith and the offense. They exceeded it again Sunday with two turnovers, including a lost fumble that ruined a scoring chance in the fourth quarter when Smith tried to pull the ball back on a read-option keeper.

His earlier interception on a crosser to Tyler Lockett was partly the result of a route-running error, according to Carroll, though he added that Smith should have abandoned the throw. He got away with a near pick earlier in the game, tossed two touchdown passes and again made plays with his legs.

Mistakes and all, Smith’s performances over the last two games should be good enough to win most of the time. But with little support from their own run game -- a 104 combined yards against the Bucs and Raiders -- and even less from their defense, it hasn’t been.

In keeping with his vow to look inward as opposed to placing blame elsewhere, Smith said he could have thrown a better ball to DK Metcalf when his fourth-quarter catch was overturned, one of two questionable calls that went against the Seahawks in big moments. That final possession of regulation ended in a punt, as did their only possession of overtime, when they only needed some 20 yards to position themselves for a game-winning field goal but went three-and-out.

“When I was in college, a coach told me about the difference between a finger pointer and a thumb pointer,” Smith said. “I've always vowed to be a thumb pointer. I'm going to look at myself hard in the mirror, watch this film, see where I can get better and help this team win games.”

With their next two games coming against offensively challenged teams, the Seahawks’ defense has a chance to get right before the 49ers rematch. They opened as 4½-point road favorites over the 3-8 Los Angeles Rams, who may again be without Matthew Stafford, who is uncertain to return this season. They should also be favored at home the following week against Sam Darnold and the 4-8 Carolina Panthers.

“We have to fix it,” safety Quandre Diggs said. “Everybody’s going to expose it if we don’t fix it. We fixed it for a little bit. It showed its head today. At the end of the day, if we don’t stop the run, we’re not going to be able to do anything.”