BOSTON — On barely three hours of sleep, without an ounce of caffeine in his system, Jackson Holliday settled into the biggest day of his young life.

The afternoon before his long-awaited MLB debut, baseball’s top prospect and the eldest son of former All-Star Matt Holliday leaned against the back wall of Fenway Park’s visitors dugout, surrounded on all sides by an impenetrable wall of cameras and reporters. The 20-year-old infielder, who has the type of face that is difficult to imagine ever aging, breezed through a lengthy media session like he breezed through the minor leagues: with the steady poise of a man twice his age.

Holliday explained how, only 19 hours earlier, he’d been informed of his call-up by Triple-A manager Buck Britton. Before the news could even sink in, Holliday began a mad dash from Harbor Park Stadium in Norfolk to Fenway Park in Boston. After calling the necessary people — his dad included — the future and present of the Baltimore Orioles packed up his apartment before driving north to Richmond with his wife, Chloe, arriving in the Virginia capital around 1:30 a.m. Wednesday. By 4:30 a.m., the Hollidays were back in the car, en route to the airport, to Fenway, to the bigs.

“Zero coffee. No caffeine,” the 2022 No. 1 pick told assembled media, including Yahoo Sports. “Maybe I’ll have a cup before the game, but I think this experience will definitely get me through the day.”

Those unfamiliar with the rosy-cheeked infielder might have taken him to appear tired, perhaps groggy from his convoluted, early-hours journey. But Holliday, raised in and molded by the major-league lifestyle, is always an understated, unbothered presence, whether he be well-rested or bleary-eyed.

“He’s been around the park his whole life. He’s so mature. It didn't look like it fazed him," Orioles third baseman Jordan Westburg told Yahoo Sports after Wednesday’s game, referring to both the moment and the lack of sleep.

After the game — in which Holliday, frankly, underwhelmed, going 0-for-4 with two strikeouts and an RBI groundout as his entire family watched from the stands — he remained predictably composed. Instead of lamenting his unfortunate foray into The Show, the scion of baseball royalty focused on the bigger picture, lauding his teammates for driving an energizing, 7-5 comeback victory punctuated by Westburg’s go-ahead, three-run blast. Because though Holliday was the headline-maker at 7 p.m., a chaotic, topsy-turvy division showdown turned out to be the real story, and the debuting phenom was merely one character.

“I'd like to have gotten a few hits, but the overall experience was pretty incredible. To go out there and win and have an RBI, I mean, it's pretty awesome,” an understandably exhausted Holliday told reporters after the game. “I can't ask for more, except for maybe, like, four hits.”

That even-keeled nature is part of what enabled Holliday to rocket up the minor leagues with such abnormal rapidity, making his MLB debut just 21 months after draft night. Sure, his natural talent and ability are striking, but ask any teammates, past or present, about Holliday, and they will focus on his vibe, dishing out clichés like free samples at the supermarket: “mature beyond his years,” “total professional,” “slow heartbeat.”

That’s because Jackson Holliday’s arrival in the major leagues, for both him and his family, was always a reasonable expectation, a rational end point, “the plan.”

“My mom says that for me and Ethan, it’s baseball first and then school,” Jackson told Yahoo Sports in an extended interview last summer, referring to his younger brother, who is a high school junior and a consensus top-10 prospect for the 2025 MLB Draft.

When asked what, if not baseball, he’d be doing for a living, an unsure Holliday replied: “Sell real estate? I don't know. I told everybody that I didn't really have a plan B, just all plan A’s. I'd probably be in Florida trying to catch fish for a living. I don't know.”

Holliday is acutely aware that he lived an abnormal childhood, that a precious few grow up inside the game, that he was afforded every possible advantage on his way to becoming a big-league ballplayer. Not only was Jackson blessed with his father’s athletic genetics, but also as an amateur, he had access to the highest-level training, equipment and travel ball, thanks to the $158 million his father earned during his career. And because he came of age around professionals, Jackson, in turn, began to mirror that ethos.

While he is a winner of the birth lottery, his ascension was not a given. One cannot coast to the bigs on nepotism alone. You actually have to use the state-of-the-art batting cage in your backyard. Effort, time and commitment are required in the process. That’s how it worked for the Hollidays.

Not wanting to push Jackson too hard or force the game upon him, Matt waited until Jackson asked to up the ante. Some time after Matt retired in 2018, Jackson went to his father and told him it was time to roll. Yes, he’d grown up in the sport, but it wasn’t until his sophomore or junior year that Jackson began to reorganize his entire existence around baseball.

“From then on,” Marlins manager and longtime friend of the Holliday family Skip Schumaker told Yahoo Sports, “it was all-in, all day, every day. And Jackson just got obsessed with it.”

That obsession, mixed with privilege, fostered greatness — or at least the promise of it. Because while Holliday’s debut was rocky and the big leagues remain daunting to even the most prepared soul, this kid was the top prospect for a reason. For many reasons.

Sure, there will be more “0-fers,” more misplays and bumps in the road, but the immense potential of Jackson Holliday lies largely in his innate ability to compartmentalize, contextualize and shrug off the gravity and scale of it all.

That these Orioles are a force with or without their newest member should lessen any additional pressure heaped upon Holliday’s shoulders. Baltimore has successfully onboarded former No. 1 overall prospects Adley Rutschman and Gunnar Henderson each of the past two seasons. Both had early scuffles, both endured, and now both are seen as generational franchise cornerstones.

Holliday’s time, too, will likely come. And thankfully for him and the Orioles, he’ll be fully rested soon enough.

“No matter how much sleep I got, I was gonna go out there and compete to the best of my abilities,” he said. “Excited to get a full night's rest tonight and get back at it tomorrow.”

Spoken like a guy who has been around a while, because, well, Jackson Holliday has.