In an offseason when a homegrown Brave like Brian McCann left in free agency for the Yankees and Jason Heyward is headed for a salary arbitration hearing, Braves fans could take solace in warm fuzzies coming from another metro Atlanta product on an otherwise cold Thursday morning.

Right-hander Lucas Sims, the Braves’ 2012 first-round draft pick from Brookwood High, got his first action at Turner Field — at least in uniform — as part of the Braves’ rookie-development week.

Sims, who was born in Lawrenceville, was one of 28 minor league prospects taking part in this week’s rookie camp, where the organization’s top young talent gets a chance to work with major league coaches and get a feel for the clubhouse and the inner workings of major-league life.

On Thursday, he played catch down the left-field line, some 60 feet below where he used to run the bases as a kid at the Coca-Cola Sky Field in the upper deck.

“I thought the fireworks out of the Coke bottle were cool and running the bases up top,” said Sims, 19, whose parents were taking him to Braves games before he was old enough to remember them. “Once you’re actually out there, even when (the stands are empty), it’s something that catches your eye. I’ll probably fall asleep thinking about it tonight.”

Sims and reliever Shae Simmons were sharing a locker in the Braves clubhouse used last year by Tim Hudson, just four down from where Sims’ boyhood favorite Brave John Smoltz had his locker.

Before this week, the only time Sims spent underneath the stands at Turner Field he was wearing a coat and tie. The first time came a couple of days after he was taken No. 21 in the draft, when he and his parents attended the retirement of Smoltz’s jersey No. 29. Then last September Sims was honored as the Braves’ organizational pitcher of the year.

In the meantime, Sims has used some of Smoltz’s advice from that June 2012 visit for motivation.

“Control what you can — your work ethic, your drive, competitiveness,” Sims said. “That’s something I carry with me.”

It’s working. In less than two years in the organization, and after his first full season at Single-A Rome, Sims is rated the Braves’ No. 1 overall prospect by Baseball America.

The power pitcher with a low-to-mid 90s fastball was 12-4 with a 2.62 ERA in 28 games last season, including 18 starts. The Braves eased him into Rome’s rotation, wanting him to work on his consistency, mechanics and lowering his pitch count, during 10 relief appearances. He made a seamless transition to the rotation, winning his last eight starts of the season, while putting up a 1.60 ERA.

“I just think it’s a conditioning and a physical maturity that you have to learn, coupled with your emotional maturity and growth that allows you to be successful in that environment,” Braves general manager Frank Wren said.

“And that’s what I think we saw over the course of the first year and a half. He finally put all that together to go along with his obvious talent. And he really had a heck of a second half last year in Rome.”

Sims, who said he has gained 25 pounds since draft day and is up to 220 on his 6-foot-2 frame, cut down on his walks during the course of last season. He worked on his alignment to the plate, something he said he continued to focus on in instructional league last fall.

“I’ll use spring training, and hopefully everything will be clicking by the time the season rolls around,” said Sims, who is expected to open the season in high Single-A Lynchburg. “I’m always going to throw kind of across my body. That how I get through the ball, how I get my extension, so I’m not expecting a perfect straight line to the plate, but there is room for improvement.”

He said his biggest improvement has come “between the ears,” adjusting to minor league life and his approach to the game.

That’s something another Braves first-rounder can attest to. Jason Hursh, another power right-hander taken by the Braves in the first round, last June, saw it in Rome. The former Oklahoma State standout made his first nine professional starts last year in Rome, where he and Sims struck up a friendship.

“It’s pretty unbelievable that he’s just come out of high school,” said Hursh, who’s also in rookie camp this week and rated the Braves’ No. 4 prospect by Baseball America. “The numbers he put up and his presence on the mound and how he understood how to set up hitters and how to get them out was pretty amazing to me. He’s mature beyond his years. All the knowledge he would have picked up in college about pitching he already has it, in my mind.”

As for the friendship? Hursh has encouraged Sims to bow hunt, while Sims is trying to get Hursh to play more golf. They already have a pretty good smack-talk dialogue going over X-box games such as FIFA soccer and Call of Duty.

A little friendly rivalry might go a long way in Sims’ development, too.

“It’s fun, keeps it relaxed,” Sims said. “I feel like we kind of took the pressure off each other.”