ARLINGTON, Texas — Six days after enjoying their most complete performance in primetime, the Bears produced the type of inconsistent effort that reminds of their youth. They went from the emotional pinnacle of this foundational season back down to earth.

The Bears were beat 49-29 by the Cowboys on Sunday at AT&T Stadium as their offense showcased progress and defense was picked apart. In the time since that dominant win in New England last Monday night, Chicago has traded veteran pass rusher and team captain Robert Quinn to Philadelphia and now was humbled by Dallas.

Here are the five takeaways from the Bears’ loss to the Cowboys.

1. Growing pains

Last Tuesday afternoon, Bears head coach Matt Eberflus struck a careful and stern tone despite the jubilation of that victory over the Patriots.

Eberflus certainly did not see a setback like this coming against the Cowboys. But he knows well that in the NFL, the results of one game don’t lead to the next. Because the Bears shined in New England, it didn’t mean they would again in Arlington.

Unfortunately for Eberflus and the Bears, it was a lesson learned the hard way.

“Look at every performance as it stands alone by itself,” Eberflus said of what the Bears can find from this last week. “When you ride the wave of momentum like this, that can be a tricky thing for a young football team. You have to look at every performance for what it is.

“One performance at a time.”

The lack of consistency also applies to the Bears’ play on each side of the football through 8 games this season. A defense that has been stout so often suffered its worst game of Eberflus’ young tenure, allowing 442 total yards of offense to the Cowboys.

Cowboys quarterback Dak Prescott was an efficient 21-of-27 for 250 yards, 2 touchdowns and an interception, while running back Tony Pollard carried 14 times for 131 yards and 3 scores, including a game-breaking 57-yard run in the fourth quarter. Linebacker Roquan Smith seemed to have Pollard for a loss in the backfield in what would’ve been a key third-down stop. Instead, he let Pollard break free while colliding with safety Eddie Jackson.

“We just got to get better,” Smith said. “We got to take this one on the chin. Hats off to those guys. But we got to get better. It’s embarrassing on the defensive side.

“We didn’t play to our standard. It’s unacceptable and it starts with me. We got to get better and we all have to get better for our individual assignments.

Meanwhile, the Bears’ offense put forth its best showing of this season as quarterback Justin Fields was 17-of-23 for 151 yards and 2 touchdowns, adding 8 carries for 60 yards and a rushing score.

But the bad from Chicago’s defense out-weighed the promise by the offense, both in sentiments and on the scoreboard. The Bears found it hard to take the good with the concerning on Sunday.

“We have to be better,” Smith said. “It’s that simple. We can’t let no one run the ball, throw the ball and do whatever — or score that many points on us. Period.”

Eberflus was eager to watch the film from this game and get a better sense for what went wrong for his Bears. But for Eberflus’ view on the sidelines, the naked eye revealed plenty from his team’s play.

The Bears can only keep pace with a dynamic opponent like the Cowboys if they play with great fundamentals. He denied the notion that his team doesn’t have the talent to compete with some of the NFL’s top teams — even if most skeptics see it differently.

“We have to be able to execute better together as a group in these instances,” Eberflus said. “We’re going to play teams that have good rosters. That’s part of football. If you want to be good, guess what? You got to play and compete against those guys.

“I don’t believe that (the Bears lack talent on defense). I don’t believe that. I believe it comes down to guys doing their jobs, coaches getting them to do it the right way together, and us playing the way we’re supposed to play. That’s what I believe.”

As the Bears build for the future, they recognize there will be growing pains along the way. They also understand the realities that come with this direction. On Wednesday afternoon — less than 48 hours from that win over the Patriots — the Bears walked off the practice field to find Quinn was being dealt to the unbeaten Eagles in exchange for a fourth-round pick.

Smith broke down in tears while addressing reporters at a podium in the Halas Hall media room, while the Bears sent Quinn off with hugs and well wishes. This young team was reminded that despite a breakthrough victory, it hasn’t arrived yet.

The Bears then came to find the harsh realization that comes with working towards sustained success. There are lessons and struggles that come with it.

“This is what the league is,” Fields said.

2. Positive strides on offense

At its core, the most important aspect of this season for the Bears is determining whether Fields can be a franchise quarterback. He inspired hope on Sunday and has continued an encouraging ascension this season.

Fields posted a career-best 120 passer rating and averaged more than 6 yards per throw and run on Sunday while posting 3 touchdowns — 2 passing and 1 rushing. What’s most important is Fields has become more confident leading offensive coordinator Luke Getsy’s scheme.

“I definitely feel like I’m growing as a runner and a thrower,” Fields said of his own play.

“I’m getting more comfortable with the offense. I think our guys are too. I think we’re growing.”

On Sunday, the Bears rushed for 240 yards of offense. It marked the third consecutive game of more than 200 yards on the ground, the first time for this franchise since 1968. That’s when the great Gale Sayers was the lead running back for Chicago.

The Bears have found their rushing success with an offense built around the dual-threat talents of Fields and a split backfield load between running backs David Montgomery and Khalil Herbert. The first-year offensive coordinator Getsy is building this identity for the skill on offense and the production is being revealed.

Fields and the Bears are starting to see the fruits of the labor pay off with a more potent offense.

“It’s good, it’s positive,” Eberflus said. “It’s a positive thing for the guys. I think the guys are starting to really gel. You can see that we’ve put in some things that are really enhancing the skill level of our players. I think it’s starting to open up some things for us. It’s a positive, for sure.”

3. Touch Down

Facing a third-and-16 late in the fourth quarter, Fields scrambled out of the pocket and found Montgomery in stride with an opening towards the marker. He was positioned to pass the chains but lost control of the football. From there, the Bears saw catastrophe ensue.

Cowboys linebacker Micah Parsons fell on the loose football as he landed to the turf of AT&T Stadium. Fields hurdled over Parsons but did not touch him down, and Parsons recognized the play was still alive. He got himself up and ran 36 yards to the end zone on a back-breaking play that cost the Bears.

“That’s my fault for just hopping over him,” Fields said. “I should’ve tackled him. I couldn’t tell you the last time I made a tackle. Just got to be aware in that situation and tackle him to make sure he’s down.”

For Eberflus, it’s a breach in basic fundamentals. Each Friday, the Bears are reminded of scenarios such as this in a video that reviews in-game situations. It’s a violations of the H.I.T.S Principle, one that will see each player receive a “loaf” back at Halas Hall on Monday.

“I felt like the momentum changed when I fumbled the ball and they recovered it for six,” Montgomery said. “That’s on me.”

4. Backfield by committee

The Bears believe in the steady play of Montgomery, who is playing through the final season of his rookie contract. They also are confident in the future of Herbert, who could also replace Montgomery as the lead back beyond this season.

So, it’s worth noting that Herbert received more carries than Montgomery for the first time in a game they both finished. Herbert rushed 16 times for 99 yards and a score while Montgomery carried 15 times for 53 yards.

It’s part of the Bears’ plan to get both Montgomery and Herbert both involved with a shared workload.

“We really like the one-two punch and we’re going to continue to do that,” Eberflus said. “They both bring an added element to the game for us, so we’re going to keep using both guys.

“We’re excited about having both of those guys for us.”

5. Trevor Time

Late in the fourth quarter Sunday, the Bears burnt through their three timeouts and forced the Cowboys to punt. But rather than bringing Fields back out with the game out of hand, Eberflus sent out backup quarterback Trevor Siemian.

“We knew the game was over,” Eberflus said.

Fields was evaluated for an injury during the second quarter on Sunday. He said it’s the result of a hip contusion he suffered during Monday night’s game. Fields believes he will be fine heading into this next week. But the Bears believed it was best to let Siemian finish the final series.

The Bears (3-5) host the Dolphins (5-3) on Sunday at Soldier Field.