DENVER -- Drew Stanton was the one player the Arizona Cardinals couldn't afford to lose on Sunday.
They did. And now the Cardinals are in trouble.
Most anything else could've gone wrong, which it essentially did, and the Cardinals would've been OK, still atop the NFC West. Any other player could've gotten injured and the Cardinals would've been fine.
But when Stanton took a seat on Arizona's bench after a second blow to the side of his head in two weeks, the Cardinals collectively held their breath. When third-string quarterback Logan Thomas began to warm up and take snaps from center Lyle Sendlein, that's when everyone inside Sports Authority Field at Mile High knew Stanton was through for the day.
Stanton walked to the locker room after suffering a concussion.
The Cardinals, who fell to 3-1 after a 41-20 loss to the Denver Broncos, have been down a quarterback since Week 1, when Carson Palmer suffered an axillary nerve contusion against San Diego. With 12 minutes left in the third quarter Sunday, they went down two.
One healthy quarterback remains on the roster, leaving Arizona at a crossroads. It's impossible to predict when Stanton will be able to play. And despite progress made this weekend in Denver, Palmer's return is still as unpredictable as the nerve in his right shoulder. It's easy to consider rushing him back, but if he can't throw hard or deep, Palmer's not an option.
Does Arizona then stick with Thomas, the rookie fourth-round pick out of Virginia Tech, and sign a veteran free agent to be his backup. Or, sign the free agent to start?
"Unless you have a crystal ball, you tell me when [Palmer's] going to come back and I'll gladly take it," Cardinals coach Bruce Arians said after the game.
Before Stanton was injured Sunday, he looked like a backup -- completing 11-of-26 passes for 118 yards. Thomas didn't look any better. His lone completion in eight attempts was his first in the NFL, and it went for an 81-yard touchdown to Andre Ellington. But on Thomas' five other drives Sunday, the Cardinals went three-and-out.
"If he's our guy next week, he's capable of beating the team we're playing," Arians said of Thomas.
That's how it is around the Cardinals. All season, they've held fast to their "next man up" motto because they've seen it work from safety Rashad Johnson replacing Tyrann Mathieu, to linebacker Larry Foote taking the place of Daryl Washington, to defensive tackle Frostee Rucker filling in for Darnell Dockett. Until Sunday, the replacements prospered.
On Sunday, nobody prospered for Arizona.
The game seemed like it was like a blur for Thomas, who hasn't practiced with the first team this season.
"Thankfully, I'm a pretty quick learner," Thomas said. "That's going to have to come in full affect. I'm going to have to be as fast as I can and complete preparation every single day and give everything every single play, every single day.
"I'm looking forward to getting the chance. If Carson or Drew are able to come back, obviously I'm just as excited to have those guys back, but if it's my turn, then it's my turn. I need to step up and be the guy."