MINNEAPOLIS — The Minnesota Vikings have been built around a stifling defense since Mike Zimmer was hired as head coach.

That foundation has developed a frightening amount of cracks, one-fourth of the way through Zimmer’s fifth season. The Vikings allowed 456 passing yards in their 38-31 loss in Los Angeles to the Rams on Thursday night, the highest total against them since 1980.

Zimmer said afterward he’s never been a part of pass defense so poor in his career, which includes successful stretches as an innovative defensive coordinator with Cincinnati and Dallas. The following afternoon, Zimmer wasn’t in any better of a mood when he was asked to assess the coverage breakdowns that led to five touchdown passes by Jared Goff.

“It was guys getting out of position. There was some misdirection plays. It was similar to what we’ve gotten before,” Zimmer said on a conference call with reporters on Friday. “Some of it was corners, some of it was safeties, some of it was linebackers, some of it was nickels, some of it was me.”

You?

“I might be over-coaching them some,” Zimmer said.

The good news is the Vikings have three extra days to recover from the Rams game and prepare for their trip to Philadelphia. The bad news is that next game is against the Super Bowl champion Eagles, who were last seen by the Vikings in that 38-7 blowout in the NFC championship game. As dominant as Zimmer’s defenses have been, certain teams with versatile and creative passing attacks have been able to exploit them. The Eagles last season and the Rams this year are two glaring examples.

Zimmer stopped short of blaming his system for the problems against the Rams, noting the 24-7 victory by the Vikings in Minnesota last season, but the most devastating plays against them on Thursday night were the result of mismatches that Rams head coach Sean McVay helped create with either pre-snap confusion or clever play-calling.

Vikings outside linebacker Anthony Barr wound up in coverage on three of the five touchdown passes, to running back Todd Gurley , wide receiver Cooper Kupp and wide receiver Robert Woods .

“They had a good game plan against us,” defensive end Danielle Hunter said. “We made more mistakes than they did, and then they ended up on top.”

The Vikings only allowed 300-plus passing yards in six games over Zimmer’s first four seasons, let alone 400-plus, with a previous high of 383 passing yards at Miami in 2014. Even the 2013 team that finished next-to-last in the league in passing defense didn’t yield a 400-yard game.

With the arrival of a new quarterback and offensive coordinator, Zimmer said, he figured the Vikings (1-2-1) could start slowly the season. They were 2-2 at the first-quarter mark last year, before finishing 13-3. So all is not lost, but this once-daunting defense has a lot of work to do.

“This team has a chance to be really, really good. One week it’s the offense. One week it’s the defense. One week it’s the special teams,” Zimmer said. “If we put it all together, we can beat any team there is.”