MIAMI – Fernando Tatis remembers the first time he saw Miguel Sano. They were playing winter ball in their Dominican Republic homeland, one a mid-30s journeyman major leaguer trying to hold on to an up-and-down career, one a 16-year-old prodigy with TNT in his bat and an effervescent smile on his face.

Tatis watched the teenager show off at the plate, swing for the fences and laugh when he missed. He saw him try to imitate some of the great shortstops of San Pedro de Macoris, where they both lived, making plays with sheer athleticism. He watched Sano, and he thought: I can help him. I want to help him. Because once, I was him.

"He had so much talent. But young guys, sometimes they don't take their talent seriously, because they think everything is forever. They think talent is enough," Tatis said. "I was that way. As a young guy, I didn't take anything serious, because I didn't see my future. But everything ends. That's what I wanted to tell him."

That's what a lot of people wanted to tell Sano, whose talent was major league before his work ethic was. He became a legend in the minor leagues, hitting home runs at the plate and errors in the field — at third base, Tatis' position, once his bodybuilder size dictated a move off shortstop — in equal numbers. His burst into the major leagues in 2015, with 18 home runs in only 80 games, confirmed that he could hit, but came with a carefree attitude about developing that talent.

And when Sano couldn't live up to his 2015 rookie promise in 2016, suffering through an injury-plagued and loss-filled season with the Twins, some bad habits became harder to overlook.

"You saw a lot of immature at-bats," Twins teammate Brandon Kintzler said. "He swung at pitches he knew he shouldn't."

From afar, Tatis recognized the symptoms. From his own career.

"It's happened to me. I remember my first day when my career started," as a hotshot, power-hitting third baseman for Texas. He was traded a year later to St. Louis, where he became famous for hitting two grand slams in an inning. He hit 34 home runs as a teammate of Mark McGwire but had a hard time holding onto a job and wound up playing for five teams, never with one for more than three seasons. And never an All-Star, either. "I remember the last moment, too — you think, it's the end," Tatis said. "It passes so fast, you cannot even believe it."

Sano went home last winter depressed about his season and motivated to fix it. He encountered Tatis again at a San Pedro ballpark, and the mentor knew his student was ready. Tatis agreed to make Sano his winter project — but he demanded dedication.

"Ground balls, every day. Every day. We'd start to hit at 3 p.m., and we'd finish around 7, and in between take a lot of ground balls," roughly 5,000 over the winter, Tatis said. "It's more work than he'd ever done before. He'd get tired, and we'd work some more. And I told him, 'You've got to do it exactly the way I show you, because you've got to do it right. We're putting a lot of energy in this, and I'm not going to waste it.' "

Sano bought in. "Tatis worked hard making me work hard," the slugger said. " 'Do more. You can do better.' He tells me this is what it takes."

The results are evident: Sano has 21 homers in 2017, or four fewer than he hit all of 2016. His .906 on-base-plus slugging, 125 points higher than a year ago, ranks 10th in the AL.

"He's grown up. He's more disciplined," said Ervin Santana, Sano's countryman and teammate. "He's not riding on just talent, but discipline, too."

Those results confirm in Sano's mind the value of maturity. He wants All-Star Games to be part of his routine. "I made sacrifices. I decided to put everything aside and work hard," Sano said. "Every day in the offseason, I'm up early to work, because I know I need to be a leader."

He takes the game seriously now, Tatis said. Yet he doesn't take himself too seriously, as teammates have noticed.

"He's a kid, he's our big kid. He's funny," Kintzler said. Sano laughs, he dances, he sings, he needles teammates from across the clubhouse. "You can see it. He knows he can be a guy in this league, he can be a real powerhouse. You see his dedication every day. … If he stays a great teammate, he's going to be a superstar."