As pro day quarterbacks tend to do, Caleb Williams entered with a script.

And as tends to happen at pro days, that script required on-field adjustments Wednesday at USC.

The expected No. 1 overall selection of the 2024 NFL Draft was scheduled to throw about 50 times in a routine featuring three receivers.

Then wide receiver John Jackson, a former USC player who finished his career at Nevada, tweaked his hamstring in an earlier drill.

Suddenly, a few routes needed to be cut. The depth of other routes, adjusted. The order and pacing had to be reconfigured to spell receivers Brenden Rice and Tahj Washington, who each now carried a more substantial workload.

“That's the irony, right?” Williams’ private quarterback coach Will Hewlett told Yahoo Sports by phone. “You've got a script, you work with the script for all these days and then the day of, it's like, ‘This happened. Listen, you're gonna run this now.’ If you didn't know, you would never have known because we changed up probably seven routes in terms of the progression [or we] cut them.

“There was even one instance where one of the guys was kind of nursing [an injury] so we weren’t going to run him full speed. An instance where Caleb was like, ‘Hey, instead of this, just do this and I'll change my drop and I'll throw this route. I got you.’”

And NFL talent evaluators, flocking to USC by the dozens Wednesday, got a valuable glance at Williams.

It’s fair to say that Williams had little to gain at his pro day. He’s overwhelmingly expected to leave the draft board No. 1, and it will be downright shocking if he is around after No. 2.

Throwing on air was thus unlikely to sway evaluators. Which is why Williams’ intangibles — his leadership, his decision-making and his poise — became nuggets that coaches, scouts and executives were eager to glean.

As the quarterback adjusted his script Wednesday, he did not flinch nor assign blame, multiple people in attendance said. One AFC scout lauded Williams’ response.

“All the QBs have practiced so much that … they handle change differently,” the scout told Yahoo Sports. “Some handle it better than others. Caleb was fine. He was going with the flow. It was easy.

“It was about Caleb showcasing his ability to get the most out of his receivers, and I thought they did a really good job of that. So credit to him.”

What Williams did and didn’t do in USC showcase

Before Williams took his first dropback, NFL Network aired a sample of the deep Rolodex of coaches and executives in attendance. The top-drafting Chicago Bears’ head coach Matt Eberflus watched from the field, while general manager Ryan Poles and Ian Cunningham looked down from a suite. Washington Commanders head coach Dan Quinn, general manager Adam Peters and offensive coordinator Kliff Kingsbury were all there in case Williams drops to them at No. 2. The New England Patriots, holders of the No. 3 pick, sent director of scouting Eliot Wolf.

These weren’t simply area scouts who would be at major universities each year for most crops of talent. These were key stakeholders, bundled in Southern California, even as Ohio State and Alabama and Texas staged their pro days across the country on the same day.

But Williams was at USC. And these evaluators wanted to see him throw for the first time this calendar year.

Williams threw over routes and hitches; down the right sideline and the left. He faked handoffs and rolled out. All but one throw came from inside the pocket.

That was a calculated decision by Williams’ team at CORTX Sports Performance: Hewlett, Tom Gormely and Denny Thompson. This wasn’t like when they wanted now-San Francisco 49ers quarterback Brock Purdy to show off his improved arm mechanics two years ago, or when they last year prepared now-Indianapolis Colts quarterback Anthony Richardson to showcase his ability to throw and to demonstrate specific concepts like the boot left that Florida hadn’t incorporated in his playbook, per Hewlett.

“We did literally one out-of-the-pocket throw because if you just flip on YouTube for three seconds, you're gonna see a million out-of-the-pocket throws,” Hewlett said. “I'm driven from a mindset or school of thought where simplicity rules. Don't make it what it’s not.”

Williams’ pro day was not an instance where he needed to flash his arm talent. Williams already won the Heisman Trophy in 2022 with 4,537 passing yards, 42 touchdowns and just five interceptions; and while he was slightly less prolific in 2023 with 30 touchdowns and five interceptions in two fewer games, his completion rating ticked up from 66.6 to 68.6%, his rushing touchdowns also up from 10 to 11.

So scouts were more looking to check a box, get a live feel for his throws and suss out any last remaining data points before final draft meetings arrive too soon.

One data point for them: Williams’ response to his script, when he completed short and intermediate throws but missed a couple deep connections and threw at least one pass behind his target. Had the script tweak led to receiver route depth confusion? Did Williams arguably throw one deep drop as he needed to, given the ball brushed its target's hands before hitting the ground?

He graded himself more harshly than evaluators, who said they typically expect a miscommunication here and whiff there. As long as the whiff doesn’t trigger an extended period of stress-induced mistakes, they don’t worry.

Williams didn’t seem to worry but also took care not to blame.

“I missed a couple of passes down the field, deep ball-wise, vertical,” Williams told NFL Network’s Steve Wyche on the NFL+ broadcast. “And then I had I think one or two, I think one, behind my receiver. So you know, work on those things.”

Hewlett chalked the response up to Williams’ work ethic and belief that “he hasn’t done what he wants to do.” He’ll work on chemistry with his receivers like he’s training with Hewlett and company to deepen his comfort in the pocket with increasing variations of footwork, including dropbacks applied to new scenarios.

“For him, there’s an expectation,” Hewlett said, “to be excellent.”

As draft nears, does Williams expect to play for the Bears?

Williams didn’t emphasize that expectation of excellence to his pass-catchers. Instead, he delivered an expectation that they have fun.

He texted them the night before. He told them again upon arrival at the stadium. And he reiterated, just in case, as drills got going.

“That’s always one of the most important things, to have fun,” Williams said. “I made sure my guys heard that a bunch of times.”

So after Williams completed his throws with a completion to Rice that sailed upward of 65 yards, the quarterback punted the ball for good measure.

He then distributed requisite hugs to scouts, coaches and general managers in attendance.

Only afterward did the real fun begin.

Williams laughed with some teammates and embraced others. One player whose weight undoubtedly would surpass the quarterback’s on a scale enveloped Williams with a sneak hug from behind. Another engaged the 2024 draft darling in a brief wrestling match that left Williams on the ground and likely at least one talent evaluator wincing.

An airborne shoulder bump — less risk, similarly enthused — capped a series of individualized teammate-to-teammate celebrations. Before his workout, Williams had already greeted now-Bears receiver Keenan Allen, who attended the workout for a player who may soon be throwing to him.

“He carried himself really well,” the AFC scout in attendance said. “All these pro days kind of take on a life of their own. Today’s pro day with Caleb kind of took on his personality: easygoing, really calm, nothing rattles him.

“And that’s kind of how the pro day went.”

Next, Williams will likely visit Chicago, and perhaps a handful of other stops. He stopped short Wednesday of saying he expected the Bears’ trade of Justin Fields to suggest their acquisition of Williams is a done deal, even after he’d said weeks ago at the scouting combine that “I don’t think I’m not going to be No. 1.”

Has his expectation evolved? Or does Williams still expect a top pick, but not know whether the Bears will own it when April nears its end?

“It's a good question; I wouldn't say it's my full expectation,” Williams said of the Bears drafting him first overall. “Obviously, things can happen. Things can change. Throughout this time, I think it's around [36] days until, you know, April 25th. And so a lot can change. You take it day by day.

“Control what you can control.”