Or, as his mentor puts it, "He wasn't even a prospect."
When Carpenter was in college, he developed a friendship with Twins veteran Torii Hunter, which blossomed after Carpenter was drafted. Carpenter's father, Rick, was integral in connecting the two, as he coached two of Hunter's sons when they were in high school.
"[My dad] was the one who told [Hunter], 'Hey, I got a son, too, that plays baseball,'" said Carpenter. "Torii reached out to me and invited me to over to hit at his house and spend some time with him."
For Hunter, it was somewhat of a given. Baseball had been good for him, and he wanted to give back by mentoring a young player, as he had done before and continues to do.
"I've been [mentoring] hundreds of players you guys don't know about. And that's what I do," Hunter said. "I've learned a lot. … So I try to give back to these young guys, and some apply it to their careers and some are kind of like, 'forget it.' And you can tell the guys that are hungry, and Matt Carpenter is definitely my No. 1 guy."
As the relationship developed, the two began training together, with Hunter picking up the tab for Carpenter to train at an expensive performance center. They ran the bases, fielded ground balls and did sprints.
"I was just lifting on my own at my dad's high school," Carpenter said. "[Hunter] took me to a place where a lot of big leaguers were training, a very high-end place with real specific work and ... really helped my career a lot."
When Hunter took a day off from training at the facility, he'd ask about Carpenter and get the same answer each time.
"They're like, 'Oh yeah, he was here,'" Hunter said. "He stays a long time. We were together eight hours a day, and you see the hard work manifest [itself] to this day."
Hunter doesn't take credit for Carpenter's success, though.
"[It's] not because of me," Hunter said. "It's because of what the parents instilled in these kids to learn and keep learning and never stop learning," Hunter said.
Hunter was always there to answer any questions Carpenter had, on topics ranging from what to expect at his first Spring Training to finances to agents.
At 29, Carpenter is now a veteran himself. Cardinals manager Mike Matheny said he sees his team's vets looking for ways to support younger players.
"It's a responsibility, I think," Matheny said.
It's a responsibility that Carpenter learned from Hunter.
"Now he's doing the same things he saw you do, and that's what it's all about," Hunter said. "Each one, teach one. Once you give it to somebody ... you can better believe they're going to do the same."
Betsy Helfand is an associate reporter for MLB.com.