The plan wasn’t for Marcelo Mayer to make his major-league debut in the middle of a doubleheader on May 24, the day Alex Bregman went down with a severe quad injury. The plan also wasn’t for the smooth-fielding shortstop to take over third base, a position he’s barely played in the minors and one of much consternation this spring when the team signed Bregman for the spot, moving Rafael Devers off his longtime position.
And yet, as Mayer surpasses one month in the majors, his time as a big leaguer has been as much a whirlwind as it’s been a natural fit. He’s, of course, still learning the ropes and not starting in every game, but he has appeared in 27 of 28 games since his debut, starting 22 of them.
On Tuesday, he played second base for the first time since his debut and posted his first three-hit game. He was back at second on Wednesday.
For all of the speculation and angst over when Mayer would debut, he’s here and more than holding his own.
“It’s been amazing,” the 22-year-old said. “It’s been a pretty hectic couple weeks. I feel like it’s gone by super fast, but slow at the same time.”
In 27 games, Mayer is hitting .208 with a .691 OPS, three doubles, a triple and four homers. Of his 22 starts, 19 have come at third base, but with Bregman expected to return within the next couple weeks, Mayer seems likely to slide to second, especially since Kristian Campbell was optioned to Triple-A Worcester last week.
Mayer has proven to be a versatile defender already. (Gary A. Vasquez / Imagn Images)
Manager Alex Cora said recently he’s comfortable with Mayer at any infield position given his strong defensive abilities.
“He’s playing third at a high level, and he doesn’t have too much experience over there,” Cora said. “The guy is a defender, and he understands everything that comes with it.”
Like every ballplayer, Mayer has been preparing for this big-league opportunity his whole life, and for the most part, expectation has met reality.
“I think as far as the baseball goes and just the day-to-day routine, it’s the same,” Mayer said. “Obviously, the game’s a little bit different considering you’re playing in front of 40,000 every day. The level of competition is a bit higher. As far as the work goes, nothing changes. The way you prepare, it’s exactly the same, but with much more of an intention to win other than just self-development.”
While still adjusting to the league, Mayer has by no means looked lost at the plate. He’s been learning on the fly how pitchers are attacking him. He clubbed his first homer at Yankee Stadium in early June and followed it up with two homers in one game at Fenway Park the following week.
Mayer goes deep!
— Red Sox (@redsox.com) June 18, 2025 at 1:33 PM
Every day in the big leagues has been a crash course in how to handle big-league pitching with its increased velocity, more advanced pitch shapes and nuanced plans of attack.
“It’s tough. I think sometimes you try to do too much,” Mayer said. “I wouldn’t necessarily say that every pitcher is that big of a difference compared to the minors, but I think just the expectations change a little bit. And sometimes you try to go out there and hit a home run every time, when in the minors, that’s not something you’re trying to do. It’s kind of it’s funny because I feel like every level I’ve gone up to, I’ve struggled to start. And then I figured it out, but that’s just part of the learning process.”
A natural shortstop, Mayer didn’t expect to be playing third so frequently in the majors, or second for that matter, though the team did start to expand his versatility more in Worcester earlier this year. In Triple A, he’d played 10 games at second and four at third in addition to 29 at shortstop. But aside from a few late-game defensive moves over to short, he’s only played third and second in the majors. Even when Bregman returns, Mayer still figures to see some time at third as Bregman ramps up his playing time after several weeks off.
“It’s crazy how things happen. That’s why it’s so important for me to always take pride in my defense and always be ready wherever,” he said. “I got a little bit of experience in spring training playing third base, and then in Triple A, I just played a few games, but mostly at second. Then I get called to the big leagues, and they’re like, ‘You’re playing third base,’ and I hadn’t taken grounders there in like a month. But I’m super comfortable in the infield, and that’s something that I take a lot of pride in. And I’m getting better every single day.”
A naturally gifted defender, Mayer has smoothly transitioned to third but still has to be mindful of certain plays.
“I wouldn’t say something is more challenging,” he said of third compared to short. “I think it’s just a different position. You have to play it way lower than at shortstop, considering at short you have more time without the ball. At third base, it’s almost all reactionary and just being athletic and making sure that you can get to a ball. And once you get to the ball, I think it’s easier because you have way more time than at shortstop.”
Mayer spent time during spring training in 2023 and 2024 in big-league camp, called up from the minor-league side for a few games at a time. But this season, alongside fellow top prospects Campbell and Roman Anthony, he spent the entirety of the spring with the big-league club. It allowed him to form relationships and get to know his teammates on and off the field.
“What helped me a lot was getting to know these guys in spring training,” he said. “It’s not like I was the guy that shot up from High A and didn’t have a chance to meet people in the big-league camp. So I think that kind of helped me a lot, creating relationships, and it made that transition that much easier with these guys. They welcomed me with open arms. They keep pushing me to be myself. Obviously, as a young guy, you’re new. You don’t want to step on anyone’s toes. But they’re pushing me to be myself, because I know that that’s going to make me play my best.”
Likewise, Cora got to know Mayer, Anthony and Campbell well in spring training, how they tick and what they react to.
“We kept them all the way to (the exhibition series in) Mexico,” Cora said of the series right before the start of the season. “That was good, just traveling with them and just to be around those two days, away from Fort Myers and the whole organization. It was good to see them perform, and the way they played that weekend, those two days. It was good having conversations with them. We sent them down, and it was a very honest conversation, and here they are. Like I said, it’s not fair to compare all of them, because they’re three different cats. They are. They are. It’s getting to know them, having dinners and all that stuff in Fort Myers.”
Mayer doesn’t have that much more big-league experience than Anthony, who was promoted on June 9, but he’s nevertheless happy to have him around.
“It’s been a long time coming,” Mayer said of Anthony’s promotion. “I feel like it’s been talked about for a very long time, but I’m super excited. I think we have a really good team, and he’s just another great addition.”
Anthony has been impressive thus far. Similar to Mayer, the surface statistics don’t tell the whole story. Anthony is hitting .114 with a .518 OPS in 15 games, but has produced mature at-bats and a balanced approach.
On Saturday in San Francisco, Anthony sparked a ninth-inning rally with a leadoff double against veteran reliever Camilo Doval. Against tough lefty starter Robbie Ray on Sunday, he drew a first-inning walk, though he did strike out in his next two at-bats. He walked again later in the game against reliever Randy Rodríguez.
“He’s been able to slow it down,” Cora said of Anthony. “He takes his walks, he hits the ball hard, he’s not trying to do too much. For a 21-year-old rookie, and hitting in the middle of the lineup for the Boston Red Sox, so far, so good.”
For Mayer, having Anthony around has only helped his transition to the majors and visa versa.
“I think I’m already pretty comfortable,” Mayer said. “But having one of my best friends on the team here helps that much more.”
(Top photo: Joe Nicholson / Imagn Images)