Bears rookie QB Justin Fields’ big leap could come sooner rather than later

The wait for rookie Justin Fields to become the Bears’ starting quarterback was brutal. He took over in Week 3, nearly a year ahead of the Bears’ original plan, but it felt like a century.

So after coach Matt Nagy made the move permanent, rather than an interim position until Andy Dalton returned from a knee injury, the last thing anyone wants to hear is that it’s still going to take awhile for Fields to launch fully.

The unfortunate truth is that rookie quarterbacks always need time and that early errors are inevitable. But the upside is that Fields came in as such an accomplished and tested college player and has shown his aptitude at every turn since joining the Bears. Maybe he won’t need so long after all.

Nagy said he saw significant change during the two weeks between Fields being thrust into starting against the Browns to his first practice as the certified starter. He leaped from trying to keep up with practice to running it. He was authoritative, poised and thorough as he prepared to visit the Raiders on Sunday.

‘‘Drastically different,’’ Nagy said. ‘‘His tempo in and out of the huddle, all of that. Your first day in there, you’re trying [to keep track of so much]: ‘I’m gonna check the clock. I’m gonna make my [middle linebacker] ID. I’m gonna do whatever I have to do.’

‘‘And that’s all a little bit slower [than Dalton]. . . . Every week it’s getting a little bit easier, a little bit faster.’’

There’s no doubt Fields’ progress during the week will manifest itself in games as he settles into the job.

That’s where a decision that’s in the Bears’ best long-term interest of getting their franchise quarterback the experience he needs could coincide with the short-term goals of making the playoffs and — regardless of whether he acknowledges what’s at stake — Nagy keeping his job. While it’s going to take years for Fields to learn everything Dalton picked up in a decade-plus, he might be a game-changer by the end of the month, if not sooner.

Of the 13 first-round quarterbacks drafted from 2017 through 2020, only Josh Rosen failed to put up a 100 passer rating in a game. The other dozen did it, on average, in their third start. The first-rounders last season — Joe Burrow, Tua Tagovailoa and Justin Herbert — each hit that mark in their second or third start.

Patriots rookie quarterback Mac Jones, who went four picks after Fields this year, did it in his debut and again in his fourth start.

Passer rating isn’t everything, of course, and Mitch Trubisky achieved his first triple-digit performance by completing 4 of 7 passes for 107 yards in his third start, but it’s a reasonable enough gauge of a quarterback’s trajectory.

Fields, for example, jumped from 41.2 against the Browns to 82.7 against the Lions, and the latter performance felt better than that. The Bears’ had the ninth-worst passer rating in the NFL during the last two seasons, and that generally tracks with how it looked.

In Fields’ case, like with Lamar Jackson and Josh Allen, that number always will be an incomplete summary of his performance because it doesn’t account for his ability as a runner. It’s called passer rating, not quarterback rating, but being a quarterback entails more than just throwing.

‘‘He’s on a certain end of the spectrum with how productive he can be when he [runs],’’ offensive coordinator Bill Lazor said when contrasting Fields with more traditional quarterbacks.

That’s an advantage for the Bears and Fields. The mere possibility of him sprinting for a first down will open opportunities for him to throw. And it seems as though he’s going to figure that — and plenty else — out very quickly.