Can Jason Heyward unlock potential?

JUPITER, Fla. -- Jason Heyward is congenial by nature and eager to blend with his new teammates in St. Louis, so he was quick to accept third baseman Matt Carpenter’s invitation to show up each day for early hitting at 7 a.m. Walk past the cage next to the Cardinals’ clubhouse at Roger Dean Stadium, and you can hear the constant thwacks as they hit balls placed on a tee by hitting coach John Mabry or his assistant, Bill Mueller.

As Heyward swings away amid the oppressive humidity, sweat rolls down his cheeks and drenches his red jersey, Carpenter sits in a folding chair and observes and provides a comment here and there. Then the two hitters change places and it’s Carpenter’s turn to swing and Heyward’s opportunity to catch his breath and offer a suggestion or two.

It’s baseball as communal enterprise and breakfast club.

“They’ve really hit it off because they both just love this game,’’ said Cardinals manager Mike Matheny. “We like using the term ‘baseball rats,’ where they just talk about it nonstop. They’re out there challenging the way the other guy thinks and trying to push each other a little bit. John and Bill have done a great job opening up an atmosphere in that batting cage, where guys might not even pick up a bat and they’re going to get better.’’

Tradition and continuity are big in St. Louis, and Heyward is the new big addition to a club with aspirations of making the postseason for the 12th time since 2000 and returning to the World Series for the third time in the past five seasons.

Heyward’s arrival was borne of unspeakable tragedy. In mid-November -- three weeks after outfielder Oscar Taveras and his girlfriend died in an automobile accident in the Dominican Republic -- Cardinals general manager John Mozeliak acquired Heyward and reliever Jordan Walden from Atlanta for starter Shelby Miller and pitching prospect Tyrell Jenkins. The trade couldn’t ease the pain of Taveras’ loss in St. Louis, but it at least provided a distraction during the grieving process and sent the conversation in a new direction.

Four months later, Heyward is balancing short-term team and individual goals with the uncertainty of where he’ll be playing a year from now. He joins former Atlanta teammate Justin Upton, now with San Diego, on the cusp of free agency in what will be a deep crop in November.

Heyward, 25, declines to speculate much on his future. It’s often said that the first trade in a player’s career is a wake-up call, because it disabuses him of the idea that he might spend his entire career with his original club. The emotional ties were compounded for Heyward because he grew up 30 miles south of Atlanta and arrived with such extravagant hype and great expectations.

Heyward burst on the scene as a 20-year-old prodigy on Opening Day in 2010, catching the ceremonial first pitch from Hank Aaron and hitting a 442-foot homer off the Cubs’ Carlos Zambrano in his first career at-bat. Chipper Jones joked that Heyward was so good, he might prompt then-manager Bobby Cox to rethink his decision to retire at the end of the season.

But with the benefit of hindsight, Heyward maintains that he never subscribed to the romantic notion of being a Brave for life.

“I always wanted to play baseball, and that’s it,’’ Heyward said. “I didn’t say, ‘I want to be drafted by a certain team,’ and I never took it for granted that I was going to be there. Growing up in Georgia, I followed the Braves closely as a kid, and I saw a lot of guys who were fan favorites end up somewhere else. You would kind of scratch your head as a fan and wonder why it happens. But it’s part of the game and part of the business.

“For me, I feel like it was a blessing in disguise. The Cardinals do their homework on work ethic and how guys fit in the clubhouse. I’m kind of honored that they said, ‘You fit in here.’ It’s been a very easy transition.’’

People who chronicle the career tracks of hot prospects inevitably think back to 2009, when Heyward and the Florida Marlins’ Mike Stanton (yes, that’s how they were referred to six years ago) were proclaimed the most heralded outfield tandem since Andrew Jones and Vladimir Guerrero graduated to the majors in 1996.

Stanton led the National League with 37 homers and a .555 slugging percentage last season, finished second to Clayton Kershaw in MVP balloting and parlayed his boundless talent and big numbers into a record $325 million contract in November.

The size of Heyward’s future free-agent windfall -- tall, grande or venti -- will be determined in large part on whether his bat can catch up with his defense.

Heyward is in an advantageous spot in St. Louis, hitting second between Carpenter and Matt Holliday in the batting order. But questions remain. Heyward is a .221 hitter with a .650 OPS in 857 career at-bats against lefties, and he has yet to put together the type of breakthrough season that leads to a true monster contract. He’s been hindered by injuries at times, and he has some length and holes in his swing that make scouts wonder if he’s ready to take the next step offensively.

“He’s been a .260 hitter with 20 homers, 70 RBIs and 15 steals,’’ said an American League scout. “I like the numbers, but those are not $20 million-a-year numbers. Sure, we can all dream. But he has (2,819) major league plate appearances, so how much is going to change? The swing is the same as his first major league at-bat.’’

Nevertheless, Heyward’s 6-5, 245-pound frame and all-around package are beyond intriguing, and one MLB executive predicts he could land a deal for eight years and more than $150 million as a free agent. Heyward and Kansas City left fielder Alex Gordon -- who will also hit the open market in November if he declines to exercise his contract option with the Royals -- are elite defenders who will serve as test cases of how much teams value outfield glove work and are willing to invest in the commodity.

Last year, Heyward ranked first in Baseball Info Solutions’ Defensive Runs Saved with a plus-32. To put that in perspective, Tampa Bay’s Kevin Kiermaier and Boston’s Daniel Nava tied for second with a plus-14 each.

The Cardinals got a glimpse of Heyward’s aggressive mindset in an early Grapefruit League game, when he served notice that he takes every base hit to right field as a personal affront.

“I think the second or third game, he was diving over the pitcher’s mound in the bullpen,’’ Holliday said. “Guys were yelling, ‘No, don’t do that! Just let it bounce!’ But he came in and dove on the mound and made a great catch.’’

As spring training winds toward a conclusion, the prospect of a third Gold Glove or 20-homer season or nine-figure contract fails to elicit much of a reaction from Heyward. He’s made enough mental notes in his first five major league seasons to learn a lot of lessons about baseball and life.

“I would be a fool not to,’’ Heyward said. “I just try to be a student of the game and get better every day, every month, every series. I have a lot ahead of me still, and I’m looking forward to that. There’s a lot more baseball out there.’’