DENVER – The result was ugly Sunday, but not because of the loss the Cardinals suffered. One of those was inevitable.

But as key Cardinals dropped out over and over, even coach Bruce Arians had to acknowledge after his team fell, 41-20, to the Broncos at Sports Authority Field that "I'm more concerned about the injuries than the score."

Defensive end Calais Campbell is out – Arians estimated three to four weeks – after hurting the MCL in his right knee on a chop block that Arians called "the dirtiest play I've ever seen." Quarterback Drew Stanton left the game with a concussion that forced rookie third-stringer Logan Thomas into an NFL game for the first time, and could force Thomas into a start next week against the Redskins.

It's possible Carson Palmer, who threw a little bit in pregame, could return for Washington from his shoulder injury, but as of now, the Cardinals (3-1) have only one healthy quarterback on the roster.

Cornerback Patrick Peterson left the game with an ankle injury but he insisted he'll be fine, although the Cards will also wait to see on tight end Troy Niklas, who was carted away with an ankle injury.

"It's about how to face adversity," Peterson said. "How to respond when guys go down. That's what it's all about. We have to learn from it and regroup."

Arians was angry about the Julius Thomas chop block that got Campbell, saying "someone has to answer for that. A fine isn't going to do it when (Campbell) is going to miss three to four weeks."

But Arians also insisted it can't impact his team.

"If you have leadership on your football team, you never lose two in a row," he said.

It will help the Cardinals won't see Peyton Manning again. The Broncos (3-1) were electric on offense, and that was thanks to Manning. His first touchdown pass was the 500th of his career, and by the time the game was over, he had thrown for four touchdowns and a career-best 479 yards.

Often the target was wideout Demaryious Thomas, whom the Cardinals entrusted to veteran cornerback Antonio Cromartie. It didn't go well. Thomas had surpassed his season total for yards in the first half alone, and finished with eight receptions for a franchise-record 226 yards and two scores.

Cromartie took the blame after.

"Everything we saw on film they did," Cromartie said. "For me, it was by far the worst game of my career."

Mistakes by the offense, however, is what put the Cardinals in a bad spot. The defense generally settled down. But what Arians was most concerned about coming into the game was inefficiency in the red zone, and that bit the Cards early.

Drops were a culprit. The Cardinals finished unofficially with six drops, spread around everywhere: Two for Ted Ginn, one each for Michael Floyd, Larry Fitzgerald, Andre Ellington and John Brown. That didn't include a slightly-errant pass from Stanton to wide-open tight end Rob Housler in the end zone that Housler could have had – the Cards settled for a field goal – or a near-miss 49-yard Stanton-to-Brown TD pass that glanced off Brown's fingers. Stanton was only 11-for-26 passing before he got hurt.

Many came on third downs that would have kept drives alive. Brown's third-down drop came right before Manning hit Thomas for an 86-yard touchdown to give the Broncos a 21-13 lead.

"(The drops) were timely ones too," said Fitzgerald, who had three catches for 57 yards. "Third downs, things like that that would have extended drives. That just kills us."

Twice, the defense intercepted Manning – once by cornerback Jerraud Powers, once by Campbell. Campbell, the Denver native, should have had a touchdown but he let Manning trip him up. Ellington ran it in from five yards out, though, and at that point, the Cards were down only 14-13.

When Stanton got hurt, though, everything changed. Campbell's absence clearly hurt the defense – the Broncos ran for five yards in the first half, but 87 in the second while Manning tossed it around – but no Stanton meant no offense.

Thomas struggled as expected. He was sacked more (twice) than he had completions (one, in eight throws). His one completion was a doozy, though, a threaded laser to Ellington, who grabbed it in stride and raced for an 81-yard touchdown.

It was a memorable first completion for Thomas. It was also not nearly enough.

Now he might have to play.

"Thankfully, I'm a pretty quick learner," Thomas said. "I'm looking forward to the chance. And if Carson or Drew can come back, I'm excited to have those guys back. But if it's my turn, I have to be the guy."

That's what Arians wanted to make sure his team understood. A win in Denver wasn't going to win the Cardinals a championship, and the way it played out – injuries and all – doesn't end the season.

"That's why we practice," center Lyle Sendlein said. "It's not like we go out on each side of the ball every day just 11 on 11. It's about trusting the next guy. Rarely is there a game where someone doesn't get hurt. There's always someone who has to go in and step up."