Stewart was an outfielder in the Chicago Cubs' organization, and he was hired during his post-playing career to scout for the Cincinnati Reds. Then, he discovered his calling as a hitting instructor in the Atlanta area.
In fact, when Heyward was a prominent 13-year-old player in a local youth league, he became one of Stewart's clients, but not before Stewart asked Heyward a question: What is your goal?
Heyward said, "I want to be a Major League player."
Now, nine years later, Stewart continues to work as Heyward's swing coach, and Heyward is the starting right fielder for his hometown Braves. He is among the primary keys to Atlanta's attempt to erase the memories of its epic collapse last September that left the team out of the playoffs on the final day of the regular season.
As for this season, Heyward was batting in the middle of the lineup during Thursday's Opening Day in New York. He struck out twice and flew out twice during the Braves' 1-0 loss to the Mets.
It didn't happen this time. But plate appearance by plate appearance, Heyward hopes to extend the good things that he flashed near the end of Spring Training into his junior year in the Major Leagues.
If so, folks will forget Heyward's sophomore slump.
OK, not slump.
What was it?
"I would call it a streak that caused a lack of success," said Stewart, who turns 36 next week. "And Jason had an injury [to his shoulder] that caused the particular streak. To me, a slump is negative. That's the last thing that a hitter needs to be focused on.
"Plus, guys who slump are not going to be in the Major Leagues, period, because they're going back to Triple-A. They don't have sound mechanics. They don't understand how to make adjustments."
Translated: Heyward's mechanics are as sound as they come, by Stewart's estimations, and Stewart applauds Heyward's ability to switch to Plans B and C when Plan A isn't working.
It's just that during Heyward's first two seasons in the Major Leagues, he has shown no signs of challenging Cal Ripken Jr.'s playing-streak record any time soon.
Take Heyward's rookie season, for instance. He injured his right thumb in the middle of the season. And, yes, he was second only to San Francisco Giants catching phenom Buster Posey in the National League Rookie of the Year Award voting. And, yes, Heyward finished with a respectable .277 batting average, .393 on-base percentage, 18 home runs and 72 RBIs.
Without that damaged thumb, Heyward's 2010 numbers would likely have been more impressive.
Then came Heyward's shoulder issues last season. They began in Spring Training, and they continued through a stretch that required Heyward to spend time on the disabled list. While appearing in just 128 games, Heyward complemented that .227 batting average with 14 homers and 42 RBIs.
Heyward's shoulder is now healthy, by the way.
"Absolutely," Stewart said. "To be quite honest, if he chose to be selfish, he could have not played at all last season. The shoulder was causing him that much pain, but he wanted to be out there for his childhood team.
"So after last season, his objective was to do everything he could to get out there and perform this year at a high level."
More recently, Heyward had numerous sessions with new Braves batting instructors Greg Walker and Scott Fletcher at the Braves' spring home in Lake Buena Vista, Fla., and at Turner Field in January for offseason workouts.
During those sessions and others, Heyward also had Braves future Hall of Fame third baseman Chipper Jones providing tips and suggestions.
Nothing was more comprehensive than Heyward's time with Stewart during the winter. Starting in late October, as the World Series was still going on without the embarrassed Braves, Heyward and Stewart met at Stewart's place -- dominated by batting cages and high-tech equipment -- three times a week for no less than an hour and a half each time.
"We broke the parts of the swing down," Stewart said. "You've got your stance, and you've got your load. You have your approach to the ball and your body alignment. Then you have your body alignment on your extension, and then the body alignment on your finish.
"Once you get those parts down, we have to make sure your tempo is good, and then it's timing."
For each of those points of emphasis, Stewart required Heyward to perform them 3,000 times before moving on. Added Stewart, "This wasn't just hitting balls off the tee, and then say, 'Remember what you're doing.' No, it was some resistance drills. It was a ton of stuff.
"We were going to do 3,000 reps so we could develop a habit."
Sounds good. But with Walker also providing more than a few offseason tweaks to Heyward's swing and Fletcher adding a few more, along with Jones, it makes you wonder if Heyward's head is about to explode whenever he leaves the on-deck circle.
"No, that won't be the case for Jason, because we started out on our end in October just getting Jason back to the basics," Stewart said. "We did things to allow him to become comfortable physically and also for Jason to be ready to receive instruction. It's kind of like having a vehicle [as in Stewart's role], and then having that vehicle customized [as in the roles of Walker, Fletcher and Jones]."
How well Heyward drives this vehicle that was heavily designed by Stewart will depend on Heyward -- you know, with Stewart whispering from the passenger's side.