If not Aaron Rodgers, then who?

GREEN BAY, Wis. – If the tests Green Bay Packers quarterback Aaron Rodgers is scheduled to undergo today don’t show enough progress for him to return from his broken collarbone, coach Mike McCarthy will have a dilemma on his hands.

Matt Flynn or Scott Tolzien -- who should start Sunday against the Atlanta Falcons?

Both of Rodgers’ backups struggled in their most recent outings.

Flynn started the 40-10 Thanksgiving day loss at the Detroit Lions and could not replicate his performance from the previous Sunday, when he relieved Tolzien in the third quarter against the Minnesota Vikings and helped rally the Packers from a 16-point, fourth-quarter deficit to a 26-26 tie – their only non-losing performance since Rodgers broke his collarbone on Nov. 4 against the Chicago Bears.

The Lions sacked Flynn seven times. Some of them were his fault for holding the ball too long, and some should be charged to the offensive line. What’s more, the Lions stacked the line of scrimmage, putting seven or more defenders in the box on nearly half of Green Bay's snaps (20 of 43 snaps, according to ESPN Stats & Information) in an effort to stop the run. That should have opened opportunities for Flynn to hit his receivers in one-on-one coverage, but he completed just 10 of 20 passes for 139 yards with no touchdowns and one interception.

Going into their final possession, the Packers had just 59 yards of total net offense.

“They dared us to throw the football at ’em,” McCarthy said. “And we tried, and they won.”

Nevertheless, McCarthy defended Flynn, saying he did not have many opportunities.

What Flynn has in experience in the Packers’ offense, he lacks in arm strength and/or willingness to throw the ball down the field. In his two appearances since he re-signed with the Packers on Nov. 12, he has averaged just 6.4 yards per passing attempt and has completed just 55.4 percent. Never a strong-armed quarterback, the arm troubles Flynn had after leaving Green Bay in free agency following the 2011 season appear to have had an adverse effect on him.

Tolzien, who has appeared in three games (including two starts) after being promoted from the practice squad on Nov. 6, has shown a better arm and more precision throwing the ball down the field. He has averaged 8.0 yards per attempt, which is much closer to Rodgers’ 8.8 yards per attempt average.

The biggest problem for Tolzien has been his decision-making. He has thrown five interceptions. Since he was pulled against the Vikings, Tolzien said he has gone back to work on his fundamentals and believes he’ll be better the next time he gets his chance, whenever that might come.

“I think certainly all those situations make you stronger in the end,” Tolzien said. “I’ve just always kind of been that way. You evaluate yourself first. You get a bad grade on a test. What could I have done better? Not what did the teacher fail to teach me? You just look at yourself first in the mirror and usually solves the problems the easiest way.”

Maybe none of it will matter if Rodgers’ tests come back positive today, and he’s able to return. But if not, McCarthy might have a difficult time deciding whether to start Flynn or Tolzien.