CARSON, Calif. – They fired an offensive coordinator who wouldn't commit to the running game.

They added two running-game specialists to their staff.

They built their offense around their star back.

They thumped the Los Angeles Chargers 39-10 on Sunday in a stadium awash in purple, to improve to 10-4 and prime an NFC North showdown with their archrival next Monday night at home.

The Vikings are where they wanted to be, but perhaps without the key to their game plans and grandest plans. So following their most lopsided victory of the season, their smiles were paired with winces, the way expensive wine might pair with moldy cheese.

Dalvin Cook, not long ago considered the Vikings' most valuable player, left the game in the third quarter with an apparent shoulder injury. He had been playing despite a similar injury. The Vikings were not forthcoming with an update, and Cook declined to speak with reporters in the locker room.

He did pull a sweater over his head without help, as AC/DC blared and teammates mimed playing drums. The song: "It's a Long Way to the Top (if You Wanna Rock 'n' Roll)."

Cook has eight days to heal before the Vikings face the Packers at U.S. Bank Stadium on Dec. 23. Those willing to speak about him spent more time praising his understudies than assessing his health.

How badly is Cook hurt? "I don't know,'' coach Mike Zimmer said. "I'm not a doctor.''

Was it an aggravation of the old injury? "No, it's not,'' Zimmer said.

Does he have a time line for Cook's return? "No, I don't,'' Zimmer said.

Quarterback Kirk Cousins shifted the conversation, saying, "It was great to see the way we ran the ball at the end of the game. They knew we were going to run the ball and we were still able to have success, which is great to see.

"I thought Mike Boone did an outstanding job running the football. I think C.J. Ham continues to show what he's capable of when the football's in his hands, on the screen pass and running it.''

Boone rushed 13 times for 56 yards and two touchdowns. Ham, a fullback who lined up occasionally at running back after Cook departed, rushed once for 5 yards and caught three passes for 13. Cook's backup, Alexander Mattison, missed the game with an ankle injury.

Cook ran nine times for 27 yards and caught three passes for 16 yards. In the first seven games this season, he surpassed 100 rushing yards five times. He hasn't rushed for 100 yards in the last seven games.

In the first 10 games of the season, he surpassed 100 yards from scrimmage eight times. He has not topped 75 in the last four games, two of which he left because of injuries. He hasn't topped 20 touches, or carries, since Nov. 10.

Two weeks ago, Cook vowed to play through pain, saying, "I've missed enough time.'' Now the Vikings may be without him, or without the best version of him, as they play for the division title.

"It's very tough to see,'' receiver Stefon Diggs said. "He's a huge part of this offense.''

"It's tough to see him go down,'' receiver Adam Thielen said. "We know how tough he is, and how much he means to our football team. I'm sure he'll be back out there again and playing and doing his thing.''

How quickly Cook recovers and how well he plays could affect the outcome of the Vikings' season and Cook's tenure in purple. He has one year remaining on his contract. Entering this season, he had played in 15 of 32 games.

Will the Vikings continue to build an offense around a running back or sign him to a massive contract, if the running back can't play in the biggest games?

These are the cruel and crucial questions facing the Vikings after their big win, and before their season's biggest night.

Jim Souhan's podcast can be heard at On Twitter: @SouhanStrib. •