The big hair, amazing athleticism and outgoing personality all made the rookie-to-sophomore transition.

But there was something different about Lonnie Walker IV as the Spurs’ squad set to participate in the 2019 Salt Lake City Summer League next week went through its first practice.

Something different that will please Spurs coach Gregg Popovich.

“He was very vocal today, and that was good to see,” said Austin Spurs coach Blake Ahearn, who will guide the team in Utah. “That’s a big thing, that leadership quality. He’s been stepping up in that area...Pop likes to see that.”

With Ahearn, Spurs assistant coach Becky Hammon and other members of Popovich’s staff at the club’s practice facility Thursday there were plenty of authoritative voices. But among the players, Walker was the vocal leader.

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“Lonnie did a great job of talking and communicating,” Ahearn said. “Even in the drills we were in, I am going to say something, and he jumps in, and that’s great. That’s what you want to see. At the end of the day, your voice gets tired — I am tired of hearing my voice — and it’s good when those guys step in, especially for Lonnie to feel comfortable to do that.”

Walker said being a leader during Summer League is all about helping the rookies get acclimated.

“I know what it takes, and I know what they are going to go through,” he said. “Whenever they need someone to talk to, I am right here. At the end of the day, if you are part of the Spurs, you are family. We’ve got each other’s backs.”

Taking on a leadership role isn’t the only positive choice the 20-year-old has made this offseason. He’s been a fixture at the practice facility ever since the season ended with the first-round playoff loss to Denver in late April, working diligently with Spurs assistant coaches Chip Engelland and Will Hardy.

“Just developing and learning things they want me to learn,” Walker said.

First and foremost, the Spurs want Walker, who they drafted 18th overall last year after his freshman season at Miami, to take steps toward becoming an elite defender. A preseason knee injury and plenty of rookie growing pains limited the Pennsylvania native to just 17 NBA games last season.

“We have talked a lot to Lonnie about defensively being locked in and keyed in,” Hammon said. “We think he has a lot of talent and ability to be a stopper for us, so we are really on him to be locked in defensively, rebounding, every possession…We’ve got a good eye on him.”

Fortunately for the Spurs, Walker has accepted the challenge.

“At first, it was like, ‘I’m just going to be a defender,’” Walker said. “But it’s more than just being a ‘defender.’ You’ve got to know where your spots are, help defense, being on the nail (stopping penetration at the middle of the free throw line)...weakside help. All of that plays a part.

“As a rookie, as much as I knew on defense, I didn’t know enough.”

NBA help defense can be complex, especially for a rookie. But all those Xs and Os that once looked like a foreign language start to make sense in a player’s second season.

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“It’s like an unconscious movement now,” Walker said. “You know when you see a screen coming what to do or not to do. Everything is starting to play along very smoothly rather than feeling like a lost cause on the defensive side.”

Another thing Walker has working for him defensively is he’s not afraid to make a mistake.

“Even the greatest defenders sometimes still get blown by,” he said. “I know what I am capable of and I know what I am not capable of. It’s all about improvement and keeping your confidence high. It’s all about rhythm and improvement, trying to get better.”

But it won’t just be about defense for Walker in Salt Lake City, Hammon said.

“Offensively, we just want him to be in attack mode,” she said. “We want to see kind of what he can get out and do.”

One thing the Spurs learned about Walker on Thursday: He won’t do any of it quietly.

“He’s growing,” Ahearn said of Walker being more vocal. “That’s a big step for him. As a coach, you always like to see players do that.”