A day after being selected fourth overall in the 2021 MLB Draft by the Red Sox, shortstop Marcelo Mayer felt like he was living a dream.

Mayer flew to Denver on Monday to take part in All-Star festivities and was wearing a home Red Sox uniform on the grounds of Coors Field as he talked to the likes of Xander Bogaerts, Rafael Devers and J.D. Martinez.

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“It was incredible. You grow up watching all those guys, and to be able to meet them is kind of crazy,” said Mayer.

After much hype and expectation that the Sox would take an ace pitcher with their highest first-round pick since 1967, the club shifted course when Jack Leiter went No. 2 overall to the Rangers.

That’s how they instead nabbed MLB Pipeline’s No. 1-rated prospect coming into the Draft. The 18-year-old Mayer recently graduated from Eastlake High School in Chula Vista, Calif.

As a side note, he is already switching his fandom.

“I grew up a Padres and Yankees fan because I grew up a huge Derek Jeter fan. That’s why I liked the Yankees,” said Mayer. “I’m now the biggest Red Sox fan.”

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Mayer fully seemed to realize the magnitude of being selected by a team with the history of the Red Sox.

“It’s super special,” Mayer said. “The Red Sox don’t usually get to pick this high in the Draft, so just to be able to join a franchise that’s very good right now is super special.”

The Red Sox had no problem shifting gears once Leiter fell off the board, especially with Mayer still available.

“What became pretty clear as the first couple picks unfolded was that we likely had these players ranked a little bit differently. We had a subset of players I think we really liked, but I think this outcome is one everybody is really, really excited about," said Red Sox director of amateur scouting Paul Toboni.

• Who is Marcelo Mayer?

Though Mayer has never set foot in Fenway Park or the city of Boston, he knows that will change in the near future.

“I’m looking forward to it,” said Mayer. “I love seafood. I love clam chowder. My trainer has the biggest Boston accent I've ever heard in my life, so he was screaming and yelling when the Red Sox took me.”

Mayer was asked which Red Sox icon he enjoyed watching the most.

“I think David Ortiz for sure,” said Mayer.

Like Ortiz, Mayer swings from the left side, but he’s more of an overall athlete and all-around player than Big Papi.

There’s something besides baseball that Mayer seems to have in common with Ortiz, too.

“I love fashion,” said Mayer. “I like looking swaggy. I just like looking good.”

The Red Sox think they’re also going to be looking pretty good once Mayer completes his development within the organization.

“I think the first thing that jumps out to you about the kid is really how he -- this sounds crazy -- but how he interacts with people. Just walking into the park and how mature he is and what a leader he is,” said Toboni. “It just jumps out at you right from the get-go.”

Intangibles are nice, but Mayer's talent and projectability are what really excite the Red Sox.

“He’s a big kid, he’s probably 6-foot-3, he’s never lifted a weight before, though, and he moves with such loose, comfortable action,” Toboni said. “That excites us as scouts because we see a lot of runway with him going forward.”

Mayer set himself apart with an impressive performance on the summer showcase circuit, where he clearly established himself as one of the top all-around talents available in this year's Draft. As Toboni alluded to, Mayer has a lean build, checking in at 6-foot-3 and 188 pounds.

He has a smooth stroke at the plate, possessing an advanced approach that includes solid plate discipline and elite bat-to-ball skills. He also has plenty of raw power that should continue to develop in the coming years.

In addition to boasting hitting prowess, Mayer is a star up the middle. From his hands to his footwork to his strong arm, the consensus among scouts is that he'll have no problem sticking at shortstop at the next level. The Red Sox expect that also.

“We absolutely do,” said Toboni. “It's one of the most appealing things about him. He's just got such purity to his game. I don't know how else to put it. His actions and the ease to which he plays shortstop, such a difficult position, there's no effort to it. We think he will get bigger and stronger, but we don't think he'll sacrifice his speed or his lateral range. That's really exciting for us.

“Obviously, the arm plays. For all those reasons, I think there's a very, very high likelihood that he's not just the guy who stays at shortstop, but an impact shortstop.”

So, with all of that context surrounding the Sox's Draft pick, what's a reasonable comp for Mayer?

“Probably [a] cross between Corey Seager and Brandon Crawford,” Toboni said. “He's got just a really advanced feel to his game, an ease to his game. I throw those names out there not to set expectations for him or anything.

“But I say Seager because Marcelo does have a little bit of a bigger build. I say Brandon Crawford, because if you watch this kid take pregame ground balls, he's one of the cockiest defenders I've ever seen in my life. I say that with positive tone behind it, where he's flipping balls with his glove, and catching balls through the legs, and going behind the back. It's not like he's showing off, it's just kind of his nature, it all comes pretty easy to him.”