The growth has happened behind the scenes, so, for the time being, fans can only take the Bears' word for it. The tests are coming, though. Twelve of them lined up for new starting quarterback Mitch Trubisky, each measuring the rookie's development, beginning Monday night against the Vikings.
"I feel like I'm ready," Trubisky said Tuesday.
Coach John Fox agrees. So off they go headfirst into the deep end, needing to keep this season and the Bears' rebuilding project afloat.
Fox characterized Trubisky's promotion as a necessary change in the wake of quarterback Mike Glennon's NFL-high eight turnovers. With the Bears in last place and sitting at 1-3 for the third time in as many seasons under Fox, he reached for a lifeline in the form of Trubisky.
It's a deviation from general manager Ryan Pace's plan to have Trubisky develop in practice behind Glennon, away from the pressure of game action.
Now the Bears have a new plan: Figure out what Trubisky can do well and accentuate that to help a team that ranks 29th in the NFL in points per game.
"They've seen what I can do throwing the ball, running around, creating plays and just really doing my job," Trubisky said. "Staying within the offense, being myself and just moving the team."
Fox spoke Tuesday only in generalities about Trubisky's recent growth. When pressed for specifics about indicators of Trubisky's readiness to succeed, he referred to "great strides" and said only that he has improved in multiple areas.
Trubisky hasn't gained any game experience since Aug. 31, and in his 12 practices since then, only Tuesday's included meaningful work with the first-string offense.
But Trubisky committed himself to maximizing scout-team work, experimenting with throws and continuing to learn to attack defenses. He stayed after practice for extra throwing.
His education extended to classroom sessions with offensive coordinator Dowell Loggains and quarterbacks coach Dave Ragone. For example, they've studied three-man fronts, which Trubisky sees more in his NFL study than he did in college.
"That's something I had to learn a lot about," he said.
They've emphasized knowing where to throw against blitzes and how to recognize disguised coverages.
"I've come a long way in learning protections," Trubisky said, "and knowing when you're hot, when you need to change protections and when the defense is (in) rotation or false rotation."
The Bears understand, though, that Trubisky is still relatively new to this. Eventually, they expect him to be the professor. For now, he's very much a student.
As a result, the Bears have pared down the offense for him.
"Mike is able to do a little more complex, intricate things within the offense," Trubisky said. "And I'll do a little more basic things."
Basic doesn't mean benign, though. Trubisky's athleticism and agility will allow the Bears to move the pocket with play-action passes and sprint-outs.
He can run the zone-read option, which could simplify coverages by requiring a safety to come down to respect his ability to run. The Bears can operate run/pass options that are dictated by the defensive alignment.
In the passing game, his accuracy was a major component to his college success, and that should improve as he gains command of the Bears offense and quickly processes what he sees.
In addition to all that, his greatest contributions might occur when plays break down and he goes off script. Several times during exhibition games, his athleticism took over on positive plays.
Alongside the Bears' optimism about Trubisky's first start is the understanding that he doesn't represent a panacea. The Bears' self-inflicted wounds have stretched throughout the team — penalties, dropped passes, missed assignments. Given Trubisky's NFL inexperience, he's not the great eraser the Bears hope he'll eventually be.
"Will he make mistakes? I'm sure," Fox said. "But I think he's ready for it, and we'll see how he responds.
Said veteran fullback Michael Burton: "For a young guy, especially at the quarterback position, he's got a great demeanor. He doesn't get too high and doesn't get too low. He's consistent … instead of riding that roller coaster."
That's probably a good description for what's ahead — roller coaster. Excitement, some fright and, if Trubisky meets expectations, a lot of fun.