After quarterback Carson Palmer suffered a season-ending injury Nov. 9, the Cardinals handed the reins to Drew Stanton, a second-round pick of the Detroit Lions in 2007.

After four seasons in Detroit and one in Indianapolis, Stanton signed with the Cardinals in 2013. He will be the X-Factor against the Falcons on Sunday.

In his first outing after Palmer went down, he out-gunned Matthew Stafford, the player he used to back up for the Lions. Stanton passed for 306 and two early touchdowns to help lead the Cardinals to a 14-6 victory.

With perhaps the No. 1 seed in the NFC on the line last week against Seattle, Stanton was not up to task.

He completed 14 of 26 passes for 149 yards against the Seahawks. He threw one interception and finished with a passer rating of 54.8. Before the Seattle game, he won all four games he finished this season.

So the Cardinals, who have Super Bowl aspirations, are not sure what they have at quarterback.

Do they have the Stanton who passed for 306 yards against Detroit’s No. 1-ranked defense?

Or, do they have the Stanton who showed up in Seattle and had the 54.8 passer rating against Richard Sherman and the Legend of Boom?

In his career, he’s played in 19 games and has made nine starts. He’s 5-4 as a starter.

Stanton has thrown 10 touchdowns and 12 interceptions in his career and has a career passer rating of 70.2.

He’ll have a chance to get well against the Falcons, who don’t mount much of a pass rush and rank last in the league in yards allowed per game (409.9) and yards passing allowed per game (284.1).

The Falcons could receive a boost with the return of safety William Moore.