It was a domination until it wasn’t.

The 49ers looked like they were about to embarrass the Seattle Seahawks at their place of business. They jumped out to a 24-3 first half lead, and seemed poised to run away with things.

Maybe it was the tryptophan in their halftime turkey, but they came out slow. A first career Brock Purdy pick-six allowed the Seahawks back in the game. But a timely sack and a Brandon Aiyuk touchdown dragged the 49ers out of their self-imposed misery, en route to a 31-13

McCaffrey, Deebo and an NFC West-winning identity

When the 49ers are at their offensive best, they are pummeling teams on the ground. They run the ball behind Trent Williams and continue pushing the issue.

That pressure forces defenses to compensate with bodies around the line of scrimmage and opens things up downfield.

That was the clear case on Thursday. Christian McCaffrey was moving arguably as well as he has all year, to the tune of 114 rushing yards and 2 TDs on 19 carries, and five receptions for 25 yards. His second touchdown was a heroic, borderline impossible effort.

Meanwhile, Deebo Samuel, who is the perpetual tone-setter, was omnipresent.

He had seven catches for 79 yards and ran four times for 15 yards and touchdown. When he is moving well, with blocking (usually Williams) ahead of him, it wears on defenses. It did on Thursday.

With the win, the 49ers move to 8-3 and (per NBC’s stats) have a 96 percent chance to win the NFC West. With the Detroit Lions’ loss to the Green Bay Packers, it also slams open the door to higher seeding opportunities. The win was massive.

Ward vs. Metcalf

By far the most entertaining matchup of the evening was Charvarius Ward against D.K. Metcalf. Geno Smith consistently tried to find Metcalf down the left sideline. Ward was having none of it.

Ward, despite being on a $13.3 million per year deal, has had moments of disappointment as of late. He has been overly grabby and consistently found himself flagged.

But on Thursday, he was a problem for Metcalf. He was a major reason that the Seahawks offense couldn’t get going early. He broke up a would-be touchdown to Metcalf, and ran him out of bounds on a handful of deep balls.

While he was dealing with calf cramps in the second half and allowed multiple underneath throws, he came up with a major stop in the end zone against Tyler Lockett.

Lockett beat him off the line, but Ward recovered to break it up. A play later, the 49ers stuffed a 3rd-and-1 failed sneak from Geno Smith. They crushed Seattle’s hopes on the following play when Nick Bosa, then Fred Warner stopped Zach Charbonnet in the backfield.

Glorious punting and timely stops

Since returning from their bye, the 49ers have been multifaceted in their schemes. They have pushed linebackers up at the line of scrimmage, frequently threatening blitzes.

When they brought blitzes on Thursday, their coverage held up long enough for pass rushers to get home, especially up the middle.

Even after they allowed the Seahawks a chance to recover, they shut the door. That came in the form of blitzes that got home consistently, usually forcing Seattle to punt.

San Francisco sacked Geno Smith six times, and everyone got in on the action. Nick Bosa had two sacks, Javon Hargrave had 1.5, both Arik Armstead and Tashaun Gipson Sr. had one, and Kevin Givens stole half of a Bosa sack.

That was aided by some great punting and successful battle to win field position.

Aside from an 66-yard return from Dee Eskridge, Seattle was generally pinned well in their own half.Mitch Wishnowsky and the 49ers special teams unit forced Seattle to start at their own 7-, 2-, 10- and 13-yard lines.

In concert with the pass rush getting home, it combined for a smothering effect on the Seahawks.