SANTA CLARA, Calif. — If Sunday night’s game against the San Francisco 49ers was supposed to be a measuring stick for the Dallas Cowboys, then the gap between the teams is ginormous.

San Francisco pinned a 42-10 loss on the Cowboys at Levi’s Stadium that left their locker room as silent as it was in January, when the Niners ended Dallas’ season in the divisional round of the playoffs.

“Didn’t see it coming,” Cowboys quarterback Dak Prescott said. “Put everything into it and got punched in the mouth. Called it a couple weeks ago humbling against Arizona, but this may be the most humbling I’ve ever been a part of. Felt good about the preparation and felt good about everything, honestly, coming into this game, matchups, and they beat us in every aspect.”

It was the second-worst loss of Mike McCarthy’s head-coaching career; only a 35-0 shutout against the New England Patriots in his first year with the Green Bay Packers in 2006 was worse. It was the largest defeat of Prescott’s career, going back to a 39-9 loss to the Philadelphia Eagles on Nov. 19, 2017, during his second season as the Cowboys’ starting quarterback.

“It’s a punch in the gut, it’s a kick in the ass, whatever phrase you want to put on it,” McCarthy said. “We’ve been knocked down, clearly. They beat us in all three phases. We will clearly acknowledge it. I’ve never been a burn-the-tape guy. I think that is a crock of s—. We’re going to go through it, make sure we’re clear on exactly what the expectations are and make sure we’re giving the players what they need to be successful. They played extremely well, and we did not.

“I thought we had taken a step as a team. I didn’t see this coming. I thought the prep was good this week. I thought we had one of our better Friday and Saturdays of the year. But it’s like we talked about before: Sometimes you have a great week of preparation and it doesn’t go so well. We did not hit the mark at all.”

A defense that allowed a league-low 10.3 points per game through four weeks gave up 21 points through six possessions. A defense that allowed two touchdown passes in the first four games saw Brock Purdy throw four. A defense that recorded 14 sacks in four games sacked Purdy just once. The run defense was hit for 170 yards and two touchdowns on 41 carries.

Offensively, it was worse for the Cowboys. Prescott completed 14 of 24 passes for 153 yards and one touchdown pass with three interceptions before he was pulled with 8:47 left to play. Running back Tony Pollard lost his first fumble since 2019, his rookie year, in the first quarter. Of the 11 possessions with Prescott at quarterback, nine of them lasted three plays or fewer.

“I don’t foresee a whole lot of winning grades coming out of this performance,” McCarthy said. “I think the most important thing for all of us, and I expressed it, just be accountable for what you did tonight, how you played. We’ve got to clean our own house up.”

The Cowboys also lost linebacker Leighton Vander Esch in the fourth quarter to a neck injury. Receiver KaVontae Turpin, who scored their only touchdown, did not return following a second-quarter ankle injury. Special teams ace C.J. Goodwin exited in the first half after sustaining a shoulder injury.

“This game is not indicative of who we are as an offense,” Dallas left guard Tyler Smith said. “This game isn’t indicative of who we are as a defense. It’s not indicative of who we are as a team.”

“I don’t foresee a whole lot of winning grades coming out of this performance. I think the most important thing for all of us, and I expressed it, just be accountable for what you did tonight, how you played. We’ve got to clean our own house up.”

Cowboys coach Mike McCarthy

The Cowboys will return to California next week for “Monday Night Football” against the Los Angeles Chargers.

“It’s still early in the season,” Dallas linebacker Micah Parsons said. “I need to help bring these guys together, and we just need to get better. There’s no such thing as losing. So tonight we just learned a lesson. We were the team at the end of the stick.”

The Cowboys have dropped their past three matchups with the 49ers, including twice in the postseason.

For the 10th time since Jerry Jones took over as owner and general manager in 1989 the Cowboys are 3-2; three times they failed to make the playoffs, including 2019.

On Sunday, the gap between the Cowboys and the Niners — who along with the Philadelphia Eagles, Dallas’ NFC East rivals, are undefeated — looked wider than ever.

“I mean, obviously, they’re further ahead than us right now,” Prescott said of the 49ers. “Yeah, so we’ve got to close that gap and be ready. To get to where we want to get, we know we’re going to have to go through this team and most likely come back to this place.”