The quarterback and head coach get more credit or blame than they usually deserve for success or failure on NFL football fields. Such has been the case for the 2018 Bears, when offense-based Matt Nagy was NFL Coach of the Year because of an elite defense, and 2019 Bears, when quarterback Mitch Trubisky has been battered on and off the field for failings not entirely his own (see: ends, tight; receivers, wide; line, offensive).

Trubisky's play over the past four games has been cited as evidence of improvement. Those included passer ratings of 131.0 and 118.1, both against the Detroit Lions, ranked 26th in opponent passer rating (99.7), 29th in yards per game 398) and (25th in points allowed per game).

But as the season moves into its decisive fourth quarter, a four-game stretch that includes three division leaders (Dallas, Kansas City, Green Bay) plus a first-runner-up with eight wins (Minnesota), while every phase and position group of the roster is tasked with ratcheting up their performances, the heaviest weight falls on Trubisky simply by virtue of his position.

The problem for the Bears is that throughout his 37-game career to date, Trubisky has failed to raise his game against better opponents. If that happens over the next four games, beginning with the Dallas Cowboys Thursday night, the Bears will be faced with a disturbing pattern in what they've hoped will develop into a franchise quarterback.

Meaning: Trubisky does not raise his game against the best. And with their season hanging by a thread, the Bears face Dallas, ranked top 10 against scoring, total yards and passing-yards.

Bad vs. Top-10'ers

Over his 37-game career, Trubisky has faced 10 top-10 defenses, using Football Outsiders DVOA ratings over the past three years. The Bears' defense was pulled out, since Trubisky doesn't play against the Bears; plus, when he did in training camp, things did not go well anyway.

In those 10 against the other top-10's, Trubisky has managed just two passer ratings higher than 90.0, a decidedly middling standard; Carson Wentz ranks 18th with a 90.0 rating this season.

Unfortunately, given Trubisky's present circumstances, there is an asterisk on those two games vs. top 10 Ds – No. 3 Baltimore (94.7) and No. 7 Carolina (101.8). Both came under John Fox and Dowell Loggains in 2017, in games when he was limited to seven and 16 pass attempts, respectively.

Trubisky's next-highest rating vs. a top-10 defense came this year against New Orleans (86.6), a result meaninglessly inflated by a fourth quarter surge after the Bears had fallen behind 36-10.

Against other top defenses, bad: In 2019, the Rams (65.1); in 2018, the Vikings (61.9 in game I, 85.9 in game II).

Against top-10 pass defenses based on opposing quarterbacks' ratings allowed, Green Bay ranks 10th with an 87.6 average. Trubisky opened the season with a 62.1 in the opening-night loss to the Packers.

Against the Chargers, who rank top 10 in based on fewest yards and points per game, Trubisky stumbled to a 75.1 that was overshadowed by Eddy Pineiro kicking problems.

Against No. 7 New England last season, Trubisky's 69.8 rating wasn't enough to overcome 14 points allowed by abysmal special teams play.

Coach Matt Nagy continues to accentuate the positive, regardless of opponent: "There were several times [in the Thanksgiving Day game at Detroit] where after the interception, he comes back and he's throwing completions. And then we were behind the chains a little bit, and he never let that rattle him. He made conviction throws.

"So overall, there's always a couple plays here or there. But overall, [the Detroit game] is probably a great example of all year long of him coming back with that next-play mentality."

That mentality projects to get some of its most difficult tests in the remaining weeks of 2019.

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Cowboys, rest of schedule confront Mitch Trubisky with top defenses, a career shortcoming so far originally appeared on NBC Sports Chicago