It's not looking good for Carson Palmer to play for the Arizona Cardinals against the San Francisco 49ers on Thursday night. That much was made evident by Cardinals head coach Bruce Arians following the team's loss to the Los Angeles Rams on Sunday. 

Palmer suffered a concussion in the second half of the game and did not return to the field. 

The veteran will now have to pass through the concussion protocol in order to play in just a few short days. Based on precedent, it appears that he will not be able to go. 

This means that veteran backup Drew Stanton will find himself under center at Levi's Stadium in front of a national audience. 

Stanton threw two ill-timed interceptions after replacing an injured Palmer during Sunday's loss. He is in no way a viable fantasy replacement for Palmer, even if the Cardinals are going up against a bad San Francisco 49ers pass defense. 

Stanton's presence under center will also have a major impact on how Larry Fitzgerald performs at receiver. Though, the biggest takeaway here will likely be a reliance on David Johnson in the run game. 

We will have plenty of time to observe and preview that game. For now, you might want to go ahead and look long and hard at the waiver wire here. Not only is Palmer injured, he's simply not performed up to the level that we anticipated heading into the season. That's also something to take into account.