Bears rookie QB Justin Fields asserting himself at Halas Hall and in games

Justin Fields threw for 175 yards and a touchdown and ran for 103 yards and a touchdown in the Bears’ 33-22 loss to the 49ers last week.

Bears rookie quarterback Justin Fields is difficult to read.

From the day he arrived at Halas Hall, he rarely has wavered from his low-key baseline. He was no more expressive after playing well against the 49ers last week than he was after imploding against the Buccaneers the week before.

In that steadiness, however, coach Matt Nagy discerned increasing assertiveness as Fields fully took hold of his role as the Bears’ starter. Say what you want about Nagy’s scheme or decisions, but he’s good at reading people and has been around Fields constantly for the last six months.

He has seen Fields’ confidence rising since he took over for Andy Dalton in Week 3, and there has been vast improvement from his debacle of a debut in Cleveland to the way he’s handling things heading into the game Monday at the Steelers. Fields has gotten progressively more authoritative with teammates, more meticulous in his mastery of the playbook and more detailed in the questions he asks in meetings.

Bears weigh risks, rewards of Justin Fields running the ball

‘‘His demeanor in the meetings is probably where you sense a lot of the growth,’’ Nagy said. ‘‘Out at practice, his tempo in and out of the huddle, his communication with the players in between plays — there’s more and more to that.

‘‘As he runs more plays together with them, there’s discussions. . . . He’s becoming a little more vocal.’’

All that development behind the scenes, as well as what he showed while throwing for 175 yards and running for 103 last week, would have been delayed a year if the Bears had stuck with Dalton, as they originally planned. It’s a tough break for Dalton that he signed expecting to be the starter and lost his spot because of an injury, but it’s what the Bears needed. Otherwise, Nagy might have kept Fields on the bench all season.

Had he done that, he likely would have avoided the five-turnover nightmare Fields endured against the Bucs. Dalton is limited, of course, but an 11-year veteran is always the safer choice over a rookie. It has been nearly two years since he had more than two interceptions in a game.

And Nagy was well aware of the probability — the inevitability — that Fields would turn in some unbearable performances at the start. There even might be more to come. A rookie quarterback’s path is rarely smooth, and Monday will be only his seventh start.

But those bad games are a necessary part of the process. There’s no way to fast-forward through all the mistakes Fields is sure to make — and to learn from — as he learns how to play in the NFL. It’s a price Nagy accepted when he made the change, even while knowing it might work against him keeping his job.

‘‘With a first-year quarterback, that is going to happen,’’ Nagy said. ‘‘You’re not going to win every game, like you maybe did in college, so how are you going to bounce back? After Green Bay and Tampa Bay, the way he handled that shows his growth of being able to mentally bounce back and have the game that he had last week.’’

Fields’ position coach, John DeFilippo, is comfortable with Fields’ path being choppy, though he hopefully won’t bottom out again the way he did against the Bucs. The hope is that the game against the Bucs was the worst it’ll get.

‘‘There are going to be some peaks and there are going to be some valleys — and everything in between,’’ DeFilippo said. ‘‘You just try to limit the valleys as much as you can.

‘‘It’s fun to watch him in those peaks, though.’’

Fields’ resilience on the field and firmer grasp of his responsibilities during the week feed each other. As he takes charge in practice and meetings, he is emboldened in games. As he plays well and stirs excitement by what he does in games, he builds his credibility with teammates.

Nagy noted that Fields has no hesitation to hold veteran teammates accountable if something isn’t done right or to instruct them to change the way they run a certain play so that it fits better with how he sees the field. At 22, he has spoken up to long-established players such as Jimmy Graham and Allen Robinson and been well-received.

‘‘He doesn’t care who you are or how many years you’ve been in this league,’’ Nagy said. ‘‘If there’s something he sees, he wants to get it right. By no means is he ever reserved. Not at all, and I love that about him.’’