Carson Palmer remains in concussion protocol and won't play Thursday night against the 49ers

Carson Palmer won’t make the trip when the Arizona  Cardinals take on the San Francisco 49ers in a Thursday Night Football showdown. The Cardinals have announced that the veteran quarterback will miss the game after suffering a concussion in Week 4.

Backup Drew Stanton will instead get the call for Arizona. The long-tenured quarterback started eight games in relief of an injured Palmer in 2014 and led the Cardinals to a 5-3 record over that span.

Stanton hasn’t seen much playing time — or success — in the years since. He’s played in just four games and hasn’t thrown a passing touchdown in the intervening seasons. After Palmer was removed from Sunday’s game, Stanton threw a pair of interceptions last week in relief work against the Los Angeles Rams.

The Cardinals didn’t make an official announcement about Palmer until Wednesday, but may have tipped their hand with a roster move on Tuesday. Arizona promoted passer Zac Dysert from the practice squad, making the Miami (Ohio) alumnus the team’s backup quarterback against San Francisco.

Arizona will rely on Stanton to turn around a season that is rapidly falling off-script. The Cardinals had the fifth-best odds to win Super Bowl 51 during the preseason. With a healthy Palmer behind center, they still managed to limp out to a 1-3 record and a spot at the bottom of the NFC West standings.

The Cardinals will face the New York Jets in Week 6 on Monday Night Football, and head coach Bruce Arians said he is "very optimistic" Palmer will be ready to return to the field for that game.