There have been many changes for Red Sox rookie Marcelo Mayer since his long-awaited call-up in late May.

The food is better, the hotels nicer. Road trips are taken on a team plane instead of a bus, and players don’t have roommates.

Much of that is par for the course for minor leaguers when they become major leaguers.

Taking over a new position, less so. Mayer is here because third baseman Alex Bregman suffered a quad strain on May 23. In response, the Red Sox called up their top shortstop prospect and moved him to the hot corner, where he’d played exactly six games in three minor league seasons.

Not that he plays like a novice. He’s already made several effortless-looking plays at third, and could move to second base when Bregman returns.

Mayer credits the veteran infielder for helping to smooth the transition. Bregman began forming relationships with the top prospects the day he reported to Red Sox spring training, which wowed Mayer.

“The first day he was here he literally sat with us for like, two hours during lunch,” Mayer told the Herald at the time. “He was just getting to know us, wanting to know what we were about, helping us. He doesn’t have to do that. He just signed for what, $120 million, and for him to do that and just talk shop with us, talk baseball, get to know us was really cool.”

The mentorship has only increased since Mayer and fellow top prospect Roman Anthony made their big-league debuts. During any given game, Bregman can be seen in the dugout offering guidance to the younger players. On Monday, he stood on the field adjusting David Hamilton’s elbow as the fellow infielder stood in his batting stance. Manager Alex Cora calls Bregman a “baseball rat.” Roman Anthony told the Herald Bregman is the most knowledgable person he’s ever met in the game.

“He’s very involved. It’s so valuable,” Mayer said of Bregman. “I think it just shows how bad he wants to succeed and how bad he wants to win. Obviously with him not playing, it just gives him more time to be able to help us. He’s a true leader. He really cares about our development and our success, and I think it shows, any time he gets a chance to help us, he does.

“It’s insane. His knowledge is like, out of this world. He tells me things sometimes that I’m like, ‘I never would have thought of that in my life. It’s just little parts of the game that he has so much experience in, and has had so much experience winning, and he knows what it takes to win. I think any time you bring a player like that into an organization, it helps.”

Reaching the majors also allowed Mayer to unlock a part of himself that lay dormant for the last few years.

“The biggest thing for me is just getting back to that feeling of wanting to win games,” he said. “You play for so long, your whole life all you want to do is win. You play in high school, with your best friends, you want to win. You go to college, you want to win. You get to the minors and it’s really not focused on winning. And then you get here and you kind of get that feeling of, all you care about is winning, again.

“That’s what I’ve enjoyed the most. I felt it as soon as I got called up. I know that the only thing that matters here is winning, and that’s kind of how I’ve approached anything I’ve done my whole life. All I want to do is win. So when I got that call, that’s really what I was most excited about, because to be honest, those games in the minors get really boring when you don’t care if you win or not. Like, it’s nice to win but it doesn’t really matter. But to me, sports, you play to win.”

In that way, Mayer feels Boston is his perfect fit.

“I love Boston, I love the fans that we have, I love how passionate they are,” he said. “Obviously we’re not where we want to be as a team and with our record, and I think we hear it a little bit, but to me I wouldn’t want it any other way. As a player who only wants to win and is super competitive, this is where you want to be.”