LOS ANGELES -- Minnesota Vikings coach Mike Zimmer struggled to wrap his head around how his defense was embarrassed for a second straight week following a 38-31 loss to the Los Angeles Rams.

The Vikings let Los Angeles put up 556 yards of offense Thursday night, allowing Jared Goff to complete 26 of 33 passes for 465 yards and five touchdowns and post a perfect passer rating (158.3) in the process.

In five years in Minnesota, Zimmer has never seen his defense struggle so badly against the pass. The same issues continue to pop up each game, with opposing receivers being left wide open, and Zimmer is at a loss for how to fix it.

"At this point, I don't know," Zimmer said. "Probably, anywhere I've ever been, I've never been this poor in pass coverage, so we're going to have to look at everything we're doing and get back to doing things correctly."

Vikings coach Mike Zimmer said he has "been concerned all year long" about his defense's poor play. Kevork Djansezian/Getty Images

Three Rams receivers -- Cooper Kupp, Brandin Cooks and Robert Woods -- posted 100-yard-receiving nights. Linebacker Anthony Barr became a pawn in L.A. coach Sean McVay's game of beating the Vikings with clever play designs, drawing the short straw on mismatches that led to touchdowns three separate times.

First it was an 8-yard TD rocket to Todd Gurley, where the reigning offensive player darted out of the backfield and left Barr flat-footed. Then, when Goff dropped back for a play-action pass in the second quarter, Kupp ran a wheel route off the back side and went 70 yards into the end zone, with Barr left in his dust. Woods' 31-yard touchdown found Barr trailing another receiver in coverage yet again.

"Just a good scheme," Barr said. "They caught us in some one-on-one coverage and were able to make a good throw and good catch."

What's troubling to Zimmer is that this is the same scheme the Vikings faced a year ago and held to seven points at U.S. Bank Stadium. Four of Goff's five passing touchdowns came in the first half, a glaring figure for a defense that let QBs run rampant in the first half in back-to-back weeks. The defense also struggled to scheme around the bootleg game to pressure the third-year quarterback.

"We made some mistakes. We left a bunch of guys open, and they have a good scheme," Zimmer said. "They don't give you too many drop-back passes where you can rush the quarterback. There's a lot of play-actions where they're blocking eight or nine guys, and it makes it difficult to get to him."

The Rams averaged just over a first down per play and notched 13 yards per pass. The pride of Zimmer's defense has been built upon limiting big plays, but the disintegration of the No. 2 pass defense from a year ago is a full-fledged liability. Minnesota has allowed a league-high 10 plays from scrimmage to go at least 30 yards or more through the first quarter of the season, with five of those gains having happened Thursday night.

"Yeah, I'm concerned," Zimmer said. "I've been concerned all year long. We have not played well defensively."