How will 49ers change from week 18? Seahawks expect switches, in 1 obvious area

The Seahawks ran wild the last time they saw the 49ers.

Seriously, nuts. A season-high 180 yards rushing wild in its victory Jan. 3 in Santa Clara, California. That clinched the Seahawks’ NFC West title and top seed in the NFC playoffs.

Now the Seahawks are expecting everything and anything from San Francisco to change its result Saturday night in the divisional-round rematch at Lumen Field. Single-high safety looks with an extra man in the box to stop the run? Changing fronts? Blitzes against running plays?

Seahawks blockers are gearing for all that, and more.

“It’s win or go home,” Seattle tight end A.J. Barner told The News Tribune in the locker room before the team’s practice Tuesday. “So I think you’re gonna get the kitchen sink, in terms of they can do whatever they think is necessary to win the game.

“We’ve just got to be prepared for all things — and both sides being prepared to play win-or-go-home football.”

The News Tribune re-watched the coaches’ “all-22” film from the Seahawks’ 13-3 victory at San Francisco 10 days ago that earned Seattle a bye through the playoffs’ first round last weekend. The Seahawks had 67 offensive plays in that game.

The TNT noted the 49ers were in a single-high safety defense, considered better for run stopping with the second safety closer to the line of scrimmage (”in the box”), 32 times. The Niners were in two-high safety alignments, to better guard against deep pass plays, 35 times.

San Francisco was in single-high safety with an extra defender near the line on only 15 of 36 snaps in the first half. That was when Seattle got 115 of its 180 yards rushing. It was the Seahawks’ most yards on the ground in a first half in two seasons.

Most of those gains were on outside-zone plays, toss sweeps and cut-buck runs by Kenneth Walker and Zach Charbonnet. Charbonnet’s 27-yard scoring run late in the first quarter came on a third and 2 with San Francisco in single-high safety defense and the second safety closer to the line.

In the second half, 49ers defensive coordinator Robert Saleh (a former Seahawks assistant under Pete Carroll) switched his defense to single-high safety with an extra run defender the majority of the time. San Francisco did that on 17 of 31 snaps after halftime.

Seattle’s biggest offensive play in the second half was on third and 17 late in the third quarter, when Walker plowed for 19 yards and a stunning first down on a sweep around right end out of shotgun formation. The Niners were of course expecting a pass. Seahawks offensive coordinator Klint Kubiak caught San Francisco in a two-deep scheme on that play.

Seattle wide receiver Jake Bobo took out the middle linebacker, the truest run defender in the middle of the field in two-deep defense, plus two other 49ers on Walker’s key run. It set up a field goal by Jason Myers for a two-score lead early in the fourth quarter.

With the way coach Mike Macdonald’s defense played, and has played most of this season leading the NFL in fewest points allowed, the game was over.

Jake Bobo took out three 49ers defenders--"not on purpose," he said---blocking outside right on Kenneth Walker's key 19-yard run 3rd & 17, 3Q of #Seahawks' NFC West title-game win at San Francisco.

"I'll take it," Bobo told me. "Just get a piece of who you're supposed to get." pic.twitter.com/vtG5EKWWjD

— Gregg Bell (@gbellseattle) January 9, 2026

The challenge for Saleh and the 49ers defense without injured All-Pros Fred Warner and Nick Bosa again Saturday night: Bringing a safety closer to the line to slow Seattle’s run will leave the back of San Francisco’s defense more vulnerable to deep pass plays from Sam Darnold to Jaxon Smith-Njigba, the NFL’s leading receiver with 1,793 yards this season.

“You’ve got to expect they might change some things up. Might bring a little more blitzes. Might play certain formations differently,” Seahawks rookie left guard Grey Zabel said Tuesday.

“At the end of the day, they are going to have a plan for us. They have a really good defensive coordinator that’s going to have something schemed up for us.

“And maybe we will have to take one or two on the chin to understand what the game plan is going to be. And we’ll continue to move forward.”

Seahawks defense expects changes, too

How the 49ers defend the Seahawks isn’t the only way Seattle’s coaches and players expect San Francisco to be different on Saturday night. Both teams prepared to run plays on offense and defense they never used in that week-18 game.

On Seattle’s side, that’s because of how “the game dictated itself,” as Macdonald likes to say. The Seahawks had the 49ers backed up against its own goal line much of the night in Santa Clara. Seattle controlled field position so decisively it changed how Macdonald and Kubiak called Seattle’s defense and offense.

For example: Macdonald chose to have the Seahawks offense go for a touchdown on fourth and goal from the 4 at the end of their opening possession. The head coach reasoned if the 49ers stopped them the Seahawks would likely be getting the ball back in prime scoring position following a defensive stop. They did: at the San Francisco 35-yard line.

Charbonnet scored the game’s only touchdown on that ensuing drive.

“There are things in the game plan that we didn’t get to. I’m sure there are things in their game plan they didn’t get to,” Macdonald said this week. “To use the whole game-declaring-itself-type thing, you don’t know how these games are going to go.

“So this game, (it’s) about a 99.999% chance it’s going to play out way different than the last one.”

That’s a pretty sure bet.

“And you got to do a great job recognizing it and making the adjustments,” Macdonald said.

One change the Niners likely want to make: Run Christian McCaffrey more, and more effectively. The Seahawks throttled San Francisco’s All-Pro running back Jan. 3. He had just 23 yards on eight carries. That was his fewest yards rushing in a game since Dec. 30, 2018, at the end of his second NFL season for Carolina. Macdonald had Emmanwori often covering McCaffrey out of the backfield on his many pass routes. It worked like few defenses have worked against McCaffrey and the 49ers.

McCaffrey had six catches, but for only 34 yards receiving, in the Seahawks’ win. He hadn’t had that many catches for so few yards without a receiving touchdown in a game in more than two years, since Christmas night 2023 for the 49ers against...Macdonald’s Baltimore Ravens defense.

Last weekend in Philadelphia McCaffrey had 37-year-old All-Pro left tackle Trent Williams back playing. Williams missed the Seahawks game two weeks ago with a hamstring injury. With Williams blocking McCaffrey looked more his lethal self against the Eagles. He caught two touchdown passes, including the game-winning one in the fourth quarter. He had 48 yards on 15 rushes against the Eagles in San Francisco’s 23-19 victory. The Seahawks haven’t allowed a 100-yard rusher in 26 consecutive games. That’s the NFL’s longest streak, and a Seattle record.

“There’s going to be wrinkles, for sure,” to the 49ers’ usual offense from coach Kyle Shahahan, Seahawks safety Julian Love said.

Seahawks middle linebacker Ernest Jones says he’s already noticed Shanahan’s 49ers offense change since Seattle played them in its last game.

Asked if as he watched San Francisco’s win at Philadelphia on television last weekend if he saw changes from the Niners, Jones said: “Yeah, we noticed a couple things.”

He smiled. He wasn’t about to reveal anymore.