THOUSAND OAKS, Calif. -- On Sunday, the Los Angeles Rams' defense was pushed around and missed tackles. When contact was made, it happened to be Rams colliding.

The Rams allowed the Dallas Cowboys to turn in a signature game, beating a .500 team for the first time in 2019 and scoring more points than they had in any game over the past five seasons.

The Rams' offense played poorly. But the defense? Perhaps worse.

"We went out there and played horrible," Los Angeles defensive tackle Aaron Donald said after the 44-21 loss. "When you play horrible, you get beat, you get beat pretty bad, and we got embarrassed."

It's not the first time it has happened this season.

The Rams (8-6) defense has proved stout, if not dominant, at times -- especially since the mid-October arrival of cornerback Jalen Ramsey, who has enabled more man coverage and has allowed the pass rush to get to the quarterback.

But the unit, which allows an average of 21.9 points per game, ranks 18th in the league in scoring. It has turned in three woeful performances, allowing opponents to score more than 40 points.

Two of those performances occurred in the past four games, moving the Rams from playoff contenders to the brink of elimination.

"We've been inconsistent overall," defensive coordinator Wade Phillips said. "We've had a couple of clunkers."

In Week 4, the Rams inexplicably allowed quarterback Jameis Winston to pass for 385 yards as the Tampa Bay Buccaneers accumulated 464 yards in a 55-40 upset.

On Monday Night Football in Week 12, with the AFC North-leading Baltimore Ravens at the Los Angeles Memorial Coliseum, quarterback Lamar Jackson evaded defenders who instead attempted to tackle players who ... didn't have the ball. Jackson put together a masterpiece, rushing for 95 yards and passing for 169 more as the Ravens scored on six consecutive drives, cruising to a 45-6 win.

That performance almost could be explained away, given Jackson has proved to be a headache for numerous defensive coordinators as he marches toward an MVP award.

But Sunday's defeat appeared different, as the Rams failed to match the physicality of the Cowboys, who entered the game with a losing record and were desperate for a victory to remain atop the NFC East.

"We practiced well, we thought we were going to play well and we didn't," Phillips said. "We thought we were going to coach well and we didn't."

Cowboys running backs Ezekiel Elliott and Tony Pollard gashed the Rams' defense, each accumulating more than 100 rushing yards. The Cowboys gained a total of 475 yards, and 176 of those yards were gained after contact, the most yards after contact for the Cowboys since 2014 and the third most by any team this season, according to ESPN Stats & Information research. And the Cowboys' 44 points? The most by the franchise since Week 17 of 2014.

"It's hard to explain," Rams coach Sean McVay said about the defense's inconsistencies. "A lot of the things last week really just boiled down to just some of the fundamentals, some of the techniques that our guys are more than capable of executing at a high level."

Veteran safety Eric Weddle, who joined the Rams in the offseason on a two-year, $10.5 million deal, provided his own theory.

"It's a momentum-type thing where we can't break the momentum that's going against us," he said. "It kind of spirals away."

Phillips grouped the loss to the Cowboys into his category of clunkers.

But Weddle viewed it differently.

"To have that game happen at that point of the season is not a clunker," Weddle said. "It's embarrassing the way we played in all three phases. That should never happen."

The Rams must regroup on a short week as they prepare to play Saturday at Levi's Stadium against the 11-3 San Francisco 49ers.

"We have fought back every time," Phillips said. "I think the attitude of our team, our defense and our whole group, we're fighters and we're going to fight back."

The Rams will be eliminated from the playoffs with a loss and become only the second team since 2009 to lose in a Super Bowl and miss the playoffs the following season. As it stands, they only have a 1.7% chance of making the postseason, according to ESPN's Football Power Index, as they must rely on winning their remaining two games and the Minnesota Vikings losing their final two contests at home to the Green Bay Packers and Chicago Bears.

"We just got to keep looking forward; we can't look back," said Rams outside linebacker Dante Fowler Jr., who is playing on a one-year, $12-million contract and has a career-high nine sacks this season. "We'll just learn from that and take it into San Francisco."

The 49ers' offense is playing as well as it has in a long time.

The 49ers rank second in the league in scoring -- averaging 29.9 points per game, their highest average since 1994 (31.6) -- and second in rushing, at 147 yards per game.

It's a different story on the other side of the ball.

"We need to play the run better," said Phillips, whose Rams rank 23rd against the run and are allowing an average of 115.6 yards per game.

And as to what causes a "clunker" and how it can be avoided as the Rams cling to the smallest of playoff hopes?

"If I knew the reason," Phillips said, "we wouldn't do it."