This time around, Mike Moustakas’ place in the clubhouse is on par with the big boys

Thirty-six nameplates adorn the tops of lockers in the visitors’ clubhouse at Angel Stadium, and his is the only one made of paper.

With the writing in black marker, the white page states Mike Moustakas, a 22-year-old Northridge native whose name stretches from shoulder to shoulder on the back of his No. 8 jersey, is indeed a big league player.

But although the Kansas City third baseman and former Chatsworth High slugger made his major league debut Friday, getting one hit and a walk in four plate appearances in the Royals’ 4-2 victory, he feels far from foreign in a major league clubhouse.

That’s because a decade ago, whenever the New York Mets were in Los Angeles to face the Dodgers, Moustakas would be the Mets’ batboy because his uncle Tom Robson was the Mets’ hitting coach.

He’d hang out with his heroes, the players he grew up watching, such as Mike Piazza, a former Dodger.

“The thing I remember the most,” the second overall pick in the 2007 amateur player draft said before Saturday’s game, “is how they treated me.”

Second baseman Edgardo Alfonzo gave him his bat and his glove. Shortstop Rey Ordonez took time out to show Moustakas, a future high school shortstop, how to play the position.

Bobby Valentine, then the Mets’ manager and one of his uncle’s close friends, took a shine to the lad, even playing the occasional joke, such as:

—Hey kid, go find the left-handed curveballs because Al Leiter (a Mets left-handed pitcher) is pitching.

—Hey kid, run to the other dugout and get the keys to the batter’s box.

“I knew I wanted to play in the major leagues when I was 2 years old,” said Moustakas, more fondly known as “Moose.”

“So being able to have that experience and hang out with those guys, it was amazing.”

Moustakas has run into some of those guys since, and in the minor leagues a few years ago, he played against a team managed by Joe McEwing, a former Met.

“Hey, I used to batboy for you,” Moustakas told him. “I’m Tom Robson’s nephew.”

“Are you kidding me?” McEwing said.

McEwing then told a story about missing a pregame meal once and asking Moustakas to make him a peanut-butter-and-jelly sandwich during the game, which the kid did.

“He remembered me exactly,” Moustakas said. “It was awesome.”

Southern California baseball fans should remember Moustakas from his playing days at Chatsworth, when he set a state record with 52 home runs, including a single-season mark of 24.

More than a few showed up for his first game: friends, family, his high school baseball coach. He left 30 tickets for them Friday, 20 more Saturday. Moustakas rewarded them Saturday with his first major league home run, a solo shot in the fourth inning against Joel Pineiro.

The Royals consider him a key piece of their future, but in the present, he’s adjusting to media attention, playing before larger crowds, brighter lights, in nicer ballparks.

His teammates did tell him to relish Friday: “This is your first and only time you get to debut in the major leagues,” he said they told him. “Just enjoy it. Soak it in.”

He did, though it was draining.

After hardly sleeping Thursday night when he was called up from triple-A Omaha, and then, after numerous interviews, playing Friday and hanging out with friends and family afterward, he collapsed into a hotel bed, exhausted but elated.

“It’s amazing to come to the ballpark every day and this is work,” he said. “This is what I do for a job.”

He said if a young batboy comes through, he’ll be sure to treat him well too.

baxter.holmes@latimes.com