GLENDALE, Ariz. – A random play doesn't define a defense. But maybe two.

A week after the Bears were burned by a perhaps once-in-a-decade Hail Mary touchdown pass, their defense inexplicably allowed the running version of that soul-destroying play in a 29-9 loss to the Cardinals in State Farm Stadium.

On a third-and-five with 12 seconds left in the first half – both teams seemed desperate to reach halftime – the Cardinals free-rolled with rarely-used running back Emari Demercado and hit the jackpot.

With Bears cornerback Josh Blackwell rushing from the left side, Demercado made a quick cut up into open space and turned on jets that the Bears defense didn't seem to know he had. The 5-9, 215-pound Demercado accelerated past the Bears' defenders into the end zone and scored an impressive 53-yard touchdown with four seconds left in the half, giving the Cardinals a 21-9 lead.

Although it happened at the end of the first half and not on the final play of the game, the Demercado touchdown had the same impact as the Commanders' Hail Mary. The game was over.

And while there were all sorts of nuances and facets to the Hail Mary debacle, the Bears players didn't have an answer to that question.

“I don’t know,” said security chief Kevin Byard. “I mean, they made a play… there’s really nothing more to say about it. They called a running play. The guy took off and scored a touchdown. I really don’t know how else to explain it.”

Cornerback Jaylon Johnson, who felt the pain of the Hail Mary game long after last week's end and identified the biggest mistake – not covering wide receiver Noah Brown – had nothing this time.

“I don’t know,” Johnson said. “We just didn’t have a good game. I just have to find a way to take him down.”

Demercado, an undrafted free agent out of TCU in 2023, came into the game with 13 carries for 116 yards and no touchdowns this season. The bears were helpless to stop him or explain what had gone wrong.

“I saw the guy running. He scored a touchdown,” Byard said when asked what happened. “I'm trying to cover my back half of the field and (I) see the guy running full speed. I tried…to hold back and see if I could force him. I don't know what his 40 time was (4.43), but he was rolling and then when I tried to get off the block some guy grabbed my arm or whatever, so… we can do that play don't give up”

It won't last forever as the Hail Mary is destined to, but Demercado's improbable touchdown run was the epitome of a surprisingly tough day for the Bears' defense.

The Bears were without three injured starters – defensive end Montez Sweat, cornerback Kyler Gordon and safety Jaquan Brisker. But the collapse against the Cardinals was unexpected.

The Bears defense had not allowed more than 21 points in the last 13 games. The Cardinals scored 21 goals in the first half alone. Without Sweat, the Bears' sometimes shaky rushing defense disintegrated. The Cardinals had 34 carries for 231 yards (6.3 average) and three touchdowns.

“Give them credit,” Byard said. “Obviously we didn't play well and they cheered for us today. We didn’t play well on either side and we have to find a way to win away from home.”

It's a critical time for the Bears, not only because their offense is unraveling, but also because the defense, once a reliable foundation, is showing its own cracks.

“It wasn’t good enough from top to bottom. We know that,” Bears linebacker TJ Edwards said. “That's not us. We have to find a way to win because that wasn't good enough for anyone. Nobody points fingers or anything. We have to get back to work.”