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The buses left Amber Cove port in the Dominican Republic on the fifth day of the St. Louis Cardinals' official cruise. All cruises have shore excursions, but the group that paid as much as $1,675 a head to socialize on this high-society trip wasn't headed for souvenir shops, waterfalls or scenic beaches.

Not on this day, anyway. These buses took off for a part of the Dominican Republic most tourists never see, with a tour guide most others would never meet.

This was Carlos Martinez's day, and this group was headed for Martinez's hometown. The 25-year-old Cardinals pitcher is a hero now in Puerto Plata, but not long ago he was just another kid growing up in the toughest neighborhood in the worst part of a rough town, a kid who found a way out through a local seminary and because he could throw a baseball harder than anyone else.

He still throws hard, and Martinez can still seem like a kid, one who jokes with teammates in the clubhouse, throws water on players in the dugout and dances around the mound after big outs. On this day, however, he was part tour guide and part goodwill ambassador to the kids he left behind on those tough Puerto Plata streets and fields.

As the buses stopped at Oscar Taveras Field, named in honor of the Cardinals outfielder who died tragically in an October 2014 car crash, the cruise patrons watched Martinez work.

"We got out and they started taking big trash bags off the bus," said Mike Claiborne, a Cardinals radio host who was on the trip. "It was bag after bag, a few dozen of them, all full of gloves and shoes and all kinds of equipment [Martinez] had collected.

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"And he didn't just drop them off and leave. He gave them out himself, and he personally made sure every kid who was there got something. Those kids just lit up."

Martinez has that effect on people, whether he is handing out gloves to disadvantaged kids or responding to a group chat set up by players on the Dominican Republic team for the recent World Baseball Classic.

"He's loud, electric, funny, fun," said New York Yankees reliever Dellin Betances, a WBC teammate.

Fans want to talk to him. Security guards at the cruise port wanted to take pictures with him.

"He was like a rock star there," Claiborne said.

Now in his fifth season with the Cardinals, Martinez is becoming an ace on and off the mound, a young player who can make people laugh while also making them respect who he is and what he is capable of.

"It was humbling," Claiborne said of Martinez's interaction with the kids in Puerto Plata. "It was a very moving day."

CONVERSATIONS ABOUT MARTINEZ USUALLY begin with a reference to the stuff he takes to the mound every five days, the fastball that can reach triple digits and the secondary pitches that go with it. But no discussion about Martinez gets very far without a mention of his dynamic personality.

"He's kind of like me," said Jose Reyes, the often-smiling New York Mets infielder and a WBC teammate. "He's always smiling, always trying to have fun. At the same time, he doesn't try to show up anyone."

That's not a coincidence.

"Jose Reyes was my idol growing up," Martinez said in an interview with Bleacher Report early this season. "When it comes to personality, we're the same."

Mark J. Terrill/Associated Press/Associated Press

Similar in the clubhouse and on the field, neither is afraid to show their excitement when something goes right.

Reyes' slogan with the Mets is "do your thing," and it fits Martinez just as well.

When he's pitching, he has as much energy as those 100 mph fastballs he throws. Your eyes are drawn to him with every pitch, just to see how he'll react.

He'll pump his fist into his glove, hop off the mound after a big out. He'll point to the sky. He's constantly in motion, always full of energy, grinning when things go well and even sometimes when they don't.

Teammates enjoy it. And as for opponents?

Dexter Fowler faced Martinez eight times in 2015 and 2016 as a member of the Chicago Cubs, before signing with the Cardinals last winter.

"You see him out on the mound and you're like, 'What is this dude doing? He's crazy,'" Fowler said. "Then you get to know him and you get it."

The Cardinals get it. Rather than asking Martinez to cut it out, they want him to channel the energy. It's a subtle difference, the key being that Martinez needs to stay under control even if he never stops moving.

"We don't want to take that out of him," manager Mike Matheny said. "That's part of his greatness. It's who he is."

Billy Hurst/Associated Press

And since 2014, Martinez has been the guy who greets teammates who hit home runs with a cup of water in the Cardinals dugout, ready to douse the "lucky" hitter.

Martinez started the prank in 2014 and says he can't even remember why. Just a random way to have fun, he says now, one that people seemed to enjoy.

It caught on, so much so that when the Cardinals planned a Martinez bobblehead giveaway this season, they came up with one that features Martinez with water cup in hand, ready to douse Matt Carpenter.

Here it is in this tweet from Cardinals TV reporter Jim Hayes:

Cardinals fans seem to love the bobblehead, but they haven't been as enamored with Martinez's hair, which he wore in a blond mohawk at times last year and in braids with silver extensions at the start of this season.

When Martinez gave up 17 runs in four consecutive subpar starts in April, some fans saw the hair as the reason. A new, less flashy hairstyle has seen Martinez roll off impressive wins over the Milwaukee Brewers, Miami Marlins and Chicago Cubs once the calendar turned to May.

If the hair was the problem, so be it. Martinez was willing to ditch the extensions in search of a win.

What he won't do is change who he is.

"Baseball is so much fun to me," he said. "When you have fun, you relax. And when you relax, it leads to better things on the field."

MARTINEZ HAS DONE WELL. His 3.32 career ERA ranks second among pitchers 25 and younger with 50 or more starts (behind Noah Syndergaard of the New York Mets).

But Martinez's pure stuff and his performances on his best days leave many believing there's more there.

Among starting pitchers, only Luis Severino of the Yankees and Syndergaard have thrown more fastballs at 97 mph-plus this season, according to MLB.com's Statcast.

"You see the electric stuff he's got and you say, 'How does anyone ever get a hit?'" said Philadelphia Phillies third base coach Juan Samuel, who watched up close as a Dominican Republic coach in the WBC.

"He obviously has the ability to become a dominant No. 1 starter," Cardinals righty Mike Leake said.

Adam Hunger/Getty Images

The Cardinals believe it will come. They see a kid with a golden arm, but also a guy dedicated to his work in the weight room and a willingness to get better in every way.

"He's a lot of fun, but his baseball IQ is very high," pitching coach Derek Lilliquist said.

Martinez has impressed the Cards in how he's starting to take on leadership responsibilities with younger players, and the club has noticed his command of English improving so he can interact with all his teammates. For now, however, Martinez still prefers to do most interviews with the help of an interpreter.

He also has had his stumbles. Martinez showed up late for a game last summer and was assessed a fine by the club, reported Mark Saxon of ESPN.com.

Martinez told Saxon it was a "one-time incident," and the team apparently agreed. The Cardinals gave Martinez a five-year, $51 million contract in February and handed him the Opening Day start two months later. To St. Louis, Martinez has the potential to be a top-of-the-rotation guy, someone who can carry on the tradition that passed from Chris Carpenter to Adam Wainwright and now to Martinez.

"He just has to slow the game down so he can be himself," Cardinals general manager John Mozeliak said. "The talent alone is going to get him so far. As a young professional, he just has to find a way to harness it. When he does, the sky's the limit."

Harnessing the energy is a constant battle. Catcher Yadier Molina regularly tells Martinez, "Breathe, breathe," just to slow him down.

"When he starts going too fast, he can't execute pitches," Lilliquist said.

When Martinez slows down and executes, he has games like the one on Opening Day against the Cubs. He pitched into the eighth inning that night, shutting out the defending champions on six hits, with no walks and 10 strikeouts.

BEFORE MARTINEZ THREW HIS first pitch to Cubs leadoff man Kyle Schwarber on that April night, he kneeled behind the mound and wrote two numbers in the dirt, with circles around them. There was an 18 in honor of Taveras and a 30 in honor of Yordano Ventura, the Dominican-born Kansas City Royals pitcher who also died in a car crash this January.

It's a ritual Martinez has repeated with Taveras' number ever since the outfielder died, and one he vows to repeat in honor of Taveras and Ventura before every start the rest of his career.

"It's very important to me," said Martinez, who now wears Taveras' No. 18 himself. "Every time I get on the hill, I think of them. It's a way to honor them, and everything we shared as friends. I know they're looking down at me and remembering."

Martinez and Taveras were best friends, two kids from Puerto Plata, a city that hasn't produced many baseball stars.

"Most of the kids there either work in the tourism industry at the beach or they work in factories," said Martinez's agent, Brian Mejia, whose parents live in the area. "The closest [baseball] academy is 3 ½ hours away."

It wasn't an easy journey.

The way Mejia tells it, Martinez grew up in one of the toughest parts of town. He never met his father and his mother died when he was young, so he was raised by his grandmother.

"The streets weren't friendly, but he worked them," Mejia said. "He shined shoes, sold fruit on the street, did whatever it took to survive."

As a kid, Martinez spent a couple years at the seminary, where at least he was guaranteed food, clothes and an education.

He turned to baseball and eventually tried out for multiple major league teams as an undersized shortstop. He was convinced he could make it, but he kept getting turned down. Seeing his strong right arm, a coach suggested he try pitching instead.

"The conversion was a long process," Martinez wrote on his blog, The Wave of Perseverance. "I wanted to quit playing baseball altogether."

He didn't quit, but the process of becoming a professional didn't get easier. The Boston Red Sox signed Martinez as a 17-year-old in 2009, but only a few weeks later, Major League Baseball voided the contract when his age and identity couldn't be verified.

He had signed as Carlos Matias, the name on the birth certificate he had. That birth certificate, it turned out, wasn't his.

The contract with the Red Sox was voided, Martinez wasn't allowed to sign with any team for a full year, and he would need accurate documentation before he could sign again.

By early 2010, he was at the Seattle Mariners complex in Boca Chica, trying out again as a pitcher. The Mariners didn't bite. The Cardinals, whose complex was nearby in the same town, heard good reports and invited Martinez to try out with them.

Once they saw his fastball, they weren't going to let him go anywhere else.

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"Moises [Rodriguez, the director of international scouting] came to me and said we need to sign this guy," said Jeff Luhnow, then the Cardinals vice president of scouting and player development and now the Houston Astros general manager. "He said it's going to take some investment higher than we've made, but we need to sign him. We got reports and sent [scout] Matt Slater to see him. Slater came back and said, 'This is the guy we want.'"

It cost a reported $1.5 million, but the Cardinals got what they wanted.

MARTINEZ WAS 18 YEARS old then, in the spring of 2010, and he wasn't the wild and crazy character he would become.

"His personality has evolved," Luhnow said. "He was much more reserved, understated. He didn't want to draw attention to himself."

Sometimes, though, he couldn't help it. That first summer, when Martinez was pitching for the Cardinals team in the Dominican Summer League, teammates began calling him "Tsunami."

"They saw how hard I threw and how well I threw," Martinez said.

The nickname stuck.

Martinez also came to be known as "Baby Pedro" for his resemblance to former major league pitcher Pedro Martinez. He liked the nickname, too, but Tsunami stuck, forming the basis of his Twitter profile and the foundation (Tsunami Waves) he formed in 2015 to help children in need.

Martinez is far from the only major leaguer with a charity. What makes his story different is his background— and the timing. Martinez was just 23 when he put the foundation together, and he was still playing for the league's $520,000 minimum salary.

"The thing you have to admire about Carlos is he was doing the outreach before [he signed a big contract]," Mozeliak said.

Martinez visited schools and set up baseball clinics in Fairmont City, Illinois, home to a sizable Hispanic population in the St. Louis area. His foundation runs a yearly bowling tournament and casino night, in addition to collecting gloves and other baseball equipment for the kids back in Puerto Plata.

"I love helping people," he said. "I have a big heart. God gives people a purpose. He helps people like me so I can turn around and help other people. Helping kids has always been a priority for me."

He sees himself in those kids. And though he has moved out of the worst part of town into a better neighborhood known as Torre Alta (Martinez is now building a house next to one owned by Al Horford of the NBA's Boston Celtics), he always remembers where he came from.

"The underdog has made it," said Mejia. "When you know his story, you gravitate to him. If you know what he's gone through, you can celebrate a strikeout right along with him."

You can celebrate with him, but celebrating like him will take some doing. You may need to jump, you may need to dance, or you may even need to grab a paper cup filled with water and douse a friend who just did something big.

You may try, but you probably can't be Carlos Martinez.

"I don't think there's any other 'Tsunami,'" Leake said. "That makes him different."

And different can be fun.

Danny Knobler covers Major League Baseball as a national columnist for Bleacher Report.

Follow Danny on Twitter and talk baseball.