Coco Montes expected the other players in Grand Junction, Colorado, to look young.

It was July 2018, and Montes was reporting for duty to the Rockies’ rookie level team after the organization selected him in the draft the month prior. He didn’t really know his teammates, and this guy in the batting cage, with blond hair and a baby face, seemed especially youthful.

The playing ability wasn’t in question. He could easily hit it out of the park and seemed just as poised as the other players, if not more.

“I was like, Wow, this guy is a stud,” Montes said.

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But this was not a new teammate. It was just Jackson Holliday, then a 5-foot-9 eighth grader on summer break, trailing after his father, Matt Holliday, who had just re-signed with the Rockies and was there on a rehab assignment.

“I could tell that he was going to be special,” Montes said. “The swing, the actions, the body, I knew he was going to get bigger. I knew he was going to be a special player. ... From what I saw from practice, I was very, very impressed for him at his age.”

This was life the only way Jackson Holliday knew it. His father played in the majors for 15 years and took his children along for the ride. Jackson was a constant presence — from the time he was a toddler during Matt Holliday’s first season in 2004 to when he was a 14-year-old budding draft prospect during his father’s last season in 2018.

Jackson Holliday is still baby-faced. But now, at 20 years old and as the top prospect in baseball, the Orioles are calling him up for his major league debut, a source confirmed to the Baltimore Banner.

He’s not scared. After all, it’s all he’s ever known.

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“That’s probably one of the main advantages of growing up in clubhouses, just the comfortability of being here and being around the dynamic and the guys and the coaches and how things work,” he said during spring training. “It’s something I saw every day. That’s where I’m most comfortable.”

Jackson’s Holliday’s childhood was one of routine. He arrived at the stadium every day hours before first pitch, the father heading off to do his pregame work and the son beelining to find someone to bother.

Jackson Holliday always wanted to play. The Rockies clubhouse was, after all, just a giant playground for him with 24 uncles. All he had to do was walk up to someone, tap him on the shoulder and suddenly he had a playmate.

Matt Holliday of the Rockies holds his son Jackson during the trophy presentation after Colorado won the 2007 National League Championship Series. (Doug Pensinger/Getty Images)

They usually happily obliged. But, as he got older, the players he was closest with started to mess with him. One time, when Jackson Holliday walked up to Ryan Spilborghs, a member of the Rockies from 2005 to 2011 and now a broadcaster, and asked him to have a catch, Spilborghs didn’t immediately follow.

He would play, he said. But only after Holliday picked up 200 baseballs.

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“That’s a lie, silly!” he yelled, with a special emphasis on the lie as he bounced down the hall toward the field, blond hair blowing behind him.

It was his catchphrase, and Matt Holliday’s teammates knew it quite well. No one remembers when or why it started; he likely just overheard it one day and ran with it.

And, boy, did he run with it.

“He was the clubhouse kid,” Spilborghs said. “He was our kid. I loved hanging out with Jackson.”

Holliday always wanted to be just like his father and dressed head to toe in uniform, even sporting the same No. 5 jersey. That was, at least, until Holliday watched “The Sandlot.” Suddenly he had a new idol and new attire.

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Rockies clubhouse manager Mike “Tiny” Pontarelli remembers when Clint Hurdle, then the team’s manager, walked out of his office one day during spring training to a stunning scene.

“Dodgers? Dodgers?” Hurdle screamed. “Matt, what’s up with that?”

Matt Holliday had no choice but to answer for his son’s fashion choices. He wasn’t becoming a fan of their rival, he explained. He had simply watched “The Sandlot” and wanted to be just like Benny “The Jet” Rodriguez, the best player on the team. He went back to wearing his Rockies hat soon after.

When Jackson Holliday was younger, he stayed at the stadium only until batting practice, his mother, Leslee Holliday, retrieving her son and bringing him back a few hours later at game time. After games, though, Matt Holliday went straight to the family room to take his son back into the clubhouse. Jackson, of course, always had his Wiffle ball and bat in hand.

When he didn’t have anyone to play with, as was often the case as players went about their postgame duties, the media became his target. As soon as a scrum started, he would zero in on a particular media member, square up his bat and hit a line drive straight into a reporter’s back.

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“He was a power hitter, even back then,” said Pontarelli, who has worked in the Rockies clubhouse since 2005.

Jackson Holliday was there for all of his father’s biggest moments in Colorado, from the three straight All-Star Games to the first, and only, Rockies World Series appearance in 2007. By 2010, they were off to St. Louis, where Matt Holliday signed a seven-year contract. Jackson Holliday was 7 now and adjusted accordingly, tossing aside his Rockies uniform for a Cardinals getup.

Jackson Holliday, then 3 years old, poses for a portrait during the Rockies' 2007 postseason run. (Photo By Glenn Asakawa/The Denver Post via Getty Images) (Glenn Asakawa/Denver Post via Getty Images)

He was stuck to his father’s side now. If Matt Holliday went to get treatment, so did Jackson. When it was time to hit, he was right there, and every conversation with his father also had to include his son.

Matt Holliday wanted his teammates to treat his son as an equal. There was only one rule: no cursing.

“It wasn’t like a kid in the clubhouse; it was an actual teammate,” said Xavier Scruggs, Matt Holliday’s teammates in St. Louis for parts of two seasons. “He was always right there. A lot of players have their kids in the clubhouse, but not as much as he was around.”

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At this point, Jackson Holliday no longer wanted to play with his Wiffle ball and bat. He was on his way to becoming a baseball star in his own right, and his pregame routine reflected it.

His father was a left fielder, but Jackson Holliday found his place in the infield. He started taking grounders every day during batting practice, lining up next to Cardinals players, including Kolten Wong, who was in Orioles camp as a non-roster invitee this spring.

“I wasn’t that good defensively yet when he was there, so I was learning with him,” Wong recalled.

As Holliday got older, he couldn’t spend as much time around his father’s clubs. He had his own teams now, with practices and games to attend. His father’s teammates, though, especially the early ones from Colorado, stayed a steady part of his life. They considered the Hollidays their family, many even living with them at various points in their lives.

On July 17, 2022, the 2007 Rockies all sat around TVs in their homes across the country. The group chat was firing away. They knew Jackson Holliday would get drafted, but they were still anxious as Commissioner Rob Manfred walked to the podium to announce the first overall pick.

“Our group was in tears,” Spilborghs said. “To see Jackson getting taken first overall was insane to us. Our group was so proud of Jackson and Matt and their family. It was a really cool emotion that we felt as a group because we felt like we were part of the Hollidays’ family.”

They’ve watched as the little boy with the blond hair and a catchphrase skyrocketed through the Orioles’ minor league system.

And now it’s time to make new memories in major league clubhouses. This time, as a big leaguer.