"This is as low as you can feel," Palmer told reporters after the game, before adding, "I kept digging us a hole."
Palmer enjoyed the best season of his career in 2015, passing for 4,671 yards and 35 touchdowns against 11 interceptions, while completing 63.6 percent of passes.
On Sunday, the 12-year vet threw four interceptions, leaving questions about the health of his finger after reports suggested he was ailing more than the team was letting on.
"Carson didn't lose the damn game," head coach Bruce Arians said Sunday. "There's nothing wrong with his damn finger."
Despite the MVP-caliber regular season, Palmer's 2015 will be remembered for two bad performances in the playoffs. He was bailed out by Larry Fitzgerald against the Green Bay Packers but ultimately exposed by a great Panthers defense on Sunday.