The White Sox's fifth-round pick in 2006 out of the University of Kentucky, Shelby was a standout middle infielder who has moved from second base to the outfield, back to second base and back to the outfield again -- where he's been full time since last season.
But as long as he keeps hitting the way he has the last two seasons, there is little doubt that his travel itinerary will keep moving him up.
Named MLB.com's White Sox Minor League Player of the Year after he hit .295 with 15 homers, 80 RBIs and a system-high 33 steals at Advanced A Winston-Salem last summer, Shelby finished second in the organization in RBIs, fifth in homers and eighth in batting. He also tied a Carolina League record with a three-homer game.
That hot summer was not far removed from the numbers he put up in his first full season (2007). With the Class A Kannapolis Intimidators, Shelby hit .301 with 16 homers, 79 RBIs and 19 steals, while posting a 22-game hitting streak midseason.
Likely bound for Double-A Birmingham when camp breaks next month, it might not appear at first glance like he has that much to work on offensively, but the 23-year-old has very definite goals to improve his game even more.
"Right now, I'm working on trying to hit the ball the other way," said Shelby. "Pulling the ball is how I end up striking out a lot, I get beat on a lot of sliders I try to pull."
And, of course, he's hoping to further improve his play in the outfield.
"Just looking ahead of me in the organization, there are a lot of good infielders in front of me," he said. "The outfield picture isn't wide open but I think there is a clearer shot to make it there, especially a guy like me. I think I bring something different to the table, a little power, I can steal some bags, whatever they want me to do."
If it sounds like he has a good grasp on the game and what it takes to get to the next level. That shouldn't be surprising, seeing as how his dad, John "T-Bone" Shelby Jr., was a big leaguer who currently is a coach with the Baltimore Orioles.
The running joke in the family has long been that John III was following in his dad's "cleatsteps" even before he could walk, turning whatever he held in his little hand into a ball.
"Ever since I was born I always had a glove or bat in my hand," he said. "I hated toys. I just liked to throw things."
The oldest of six children (five boys and a girl), he talks to his dad pretty much every day, but there are actually more members of the immediate Shelby family that serve as inspiration to John III, who is nicknamed "Treybone."
But ask him who he would trade places with for one day and he doesn't hesitate -- his 21-year-old brother, Jeremy.
Jeremy, two years younger than John, is a red-shirt senior on the baseball team at Grambling State, but he's overcome more than just a few position shifts.
"He's my 'little big' brother, and he overcame Hodgkins Disease in high school and it never fazed him," Shelby said. "He got through it like it was nothing, and he really inspired me to be stronger as the oldest brother."
Jeremy is healthy and happy and continuing to be an inspiration to friends and family, dabbling on the side in singing Christian rap, among other things.
"He's doing fine now, totally clean, nothing bothering him," said Shelby. "He walks the walk and he talks the talk."
MLB: Of what accomplishment, on or off the field, in your life are you the proudest?
John Shelby: A few things. Definitely getting engaged last year. Also, I love how my brothers look up to me. Having their respect so I know it's not about me, it's about my paving the way for them. And as far as baseball, in college I only hit .291 as a junior so being able to bat over .300 in pro ball is a nice accomplishment.
MLB: What do you think you'd be doing now if you weren't playing baseball?
JS: I don't even want to think about it (laughs). But I'm very involved in our church. I think I would finish up school and get married. What else can I do but play baseball?
MLB: Everyone has a "hidden talent." What's yours?
JS: Everyone else in my family has a hidden talent, they can draw or sing, but I don't have one. My hidden talent, I guess, is making people laugh. I have a dry sense of humor.
MLB: What is the worst job you've ever had?
JS: I haven't had a lot of jobs, but this offseason I got a job as a security guard for Kentucky basketball games. I thought I'd get to see the games, to peek in and watch them, but I couldn't.
MLB: What is your guiltiest TV pleasure?
JS: The only thing I watch is "King of Queens." I love that show. It always seems to relate to me. Other than that, I always have ESPN on but I'm not a big TV guy.
MLB: Which aspect of life in the Minors do you find to be the biggest challenge and why?
JS: Being away from family is the toughest thing. The baseball part isn't tough, it's what we love to do. But if you're in a slump, you want someone to be there and give you a hug and you only have the phone.
MLB: If you were commissioner for a day, which one rule would you change?
JS: They should have blood tests for steroids. You can't fake blood. And there should be more off days.