(CBS Chicago/CBS Local) — Conversations about both the Chicago Bears and Minnesota Vikings, their Week 4 opponent, always come around to quarterbacks. (In a competitive NFC North, featuring the Green Bay Packers’ Aaron Rodgers and the Detroit Lions’ Matthew Stafford, it’s not surprising.) Neither the Bears’ Mitchell Trubisky nor the Vikings’ Kirk Cousins have become the player their teams had hoped they would by this point. And for teams with playoff aspirations, that can be an issue.

Trubisky’s play hasn’t measured up to his breakout 2018 showing, In fact, aside from his three-touchdown quarter against the Washington Redskins on Monday night, it’s been mostly forgettable. He has weapons around him — Allen Robinson, Taylor Gabriel, Tarik Cohen –if he can keep them involved in the offense. But the Bears managed just 17 total points in their first two games against the Green Bay Packers and Denver Broncos, both of whom field defenses more comparable to the Vikings’.

Khalil Mack #52 of the Chicago Bears runs off the field against the Washington Redskins in the second half at FedExField on September 23, 2019 in Landover, Maryland.

Khalil Mack (Photo Credit: Rob Carr/Getty Images)

Cousins’ performance to date also leaves something to be desired. He’s only thrown 63 passes so far this season. (By comparison, Aaron Rodgers threw 53 last night.) And when asked to lead the offense, he has sometimes faltered, like in his 14-32 showing in Week 2 against those same Packers. But usually the Vikings don’t ask.

Expectations have still been high since he arrived before last season, given the size of his contract. While that isn’t entirely fair, it’s to be expected. “Cousins hasn’t had to do much over the first couple weeks of this season, notes Rick Ritter, anchor for WJZ in Baltimore and host of the Ravens postgame show Purple Connection.

“This team is running through Dalvin Cook, the third-year running back,” Ritter continued. “He finally seems to be healthy. And he’s absolutely torching the NFL right now. The Vikings [are] only behind the Ravens in rushing offense per game.”

>>READ: Vikings-Bears Preview: Cousins, Trubisky Face Daunting Defenses

Cook has carried the ball 57 times so far for 375 yards and four touchdowns. He’s averaging 125 rushing yards per game and 6.6 yards per carry, leading both categories by hefty margins, among those RBs with enough carries to matter.

“Cook has certainly looked the part [of a featured back], not only running between the tackles, also catching the ball out of the backfield,” according to Ritter. “And when he can do that, it opens everything else up for them. We know they’ve got studs on the outside, Stefon Diggs, Adam Thielen.”

The Bears, who don’t allow many rushing yards, present an interesting threat to the Vikings and Cousins. Khalil Mack gave the Washington Redskins fits on Monday night, helping to limit Adrian Peterson to just 37 yards and harassing Case Keenum in the pocket. And if he and that stout Bears defense, which hasn’t allowed a 60-yard rusher yet, can contain Cook, then Cousins will need to step up.

The verdict is still out as to whether Cousins can show up for the big game. And with the Packers and Lions both looking good so far this season — last night’s Packers loss notwithstanding — this is a big game.

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“The Bears, [have] one of the top rushing defenses in the League,” notes Ritter. “I’m looking at Cook versus Khalil Mack here. If they can contain Mack, if they can can get Cook going, I think they pull this one out. If they can’t contain Mack, it might be a long day for Kirk Cousins and that Vikings offense.”

The Bears play the Vikings @ 3:25 p.m. CT on CBS.