Fresno State’s Aaron Judge slugs during the 2012 College Home Run Derby. Judge will participate in the 2017 MLB Home Run Derby, this time as a New York Yankees rookie.(Fresno State Athletics via The New York Times)

Mason Katz was at the airport in Boston, waiting to fly to Omaha, Nebraska, for the 2012 College Home Run Derby, when he noticed another baseball player from the Cape Cod League sitting near the gate.

So he walked over to introduce himself to Aaron Judge.

“He stood up to shake my hand, and I remember looking straight up,” said Katz, who is 5 feet 9 inches tall. When they boarded the plane, Judge was so busy chatting with Katz that he hit his head on the doorway entering the plane. “I couldn’t do that if I jumped,” Katz said.

Judge, who stands 6-7 and weighs 282 pounds, has remained an outsize figure in his rookie season with the New York Yankees, hitting a major league-leading 30 home runs, many of them prodigious blasts. He has almost instantly become one of the most captivating players in baseball.

Judge, who will start in right field for the American League in Tuesday night’s All-Star Game after being the league’s leading vote-getter, will first take center stage Monday in the All-Star Home Run Derby. He will be trying to unseat the defending champion, Giancarlo Stanton, who is 6-6, 245 pounds, and will be on his home turf in Miami.

For weeks, Major League Baseball officials had been pleading for Judge to enter the showcase event. This was far different from the only other home-run-hitting contest he entered — the one in Omaha, site of the College World Series, in 2012. When Judge, who had hit four home runs that season as a sophomore at Fresno State, received his invitation, he asked, “Are you sure you want me out there?”

But at the end of the Omaha derby, there was little question Judge belonged.

Down to his last out and trailing by one home run, Judge hit four consecutive balls out of the ballpark to win the contest, much to the delight of the 22,403 in attendance, including Bo Jackson. It was by far the biggest crowd for which Judge had performed.

“In college, on good nights, maybe you’d have 10,000 people,” Judge said. “After you hit one and two and three, they get a little excited and you can hear them, and you feed off that.”

That night in Omaha remains a cherished moment, not just for Judge, but for many of the eight participants in the derby. One, Virginia’s Derek Fisher, is a top prospect for the Houston Astros. Another, Georgia Tech’s Daniel Palka, is in Triple-A ball for the Minnesota Twins. Three others are playing in independent leagues, not ready to give up on their dreams: Virginia Tech’s Tyler Horan, College of Charleston’s Daniel Aldrich and LSU’s Katz. Two others — South Carolina’s L.B. Dantzler and Tennessee Tech’s Zach Stephens — have retired.

“It was a blast,” said Horan, who had the lead until Judge’s late flurry. “Most of those guys I only met the day before, but you’re joking and goofing around as if you played together the whole season.”

In the insular world of baseball, their paths have continued to cross. Aldrich played in the Yankees’ system; Fisher chatted with Judge in spring training; Horan and Judge each made the South Atlantic League All-Star Game in Class A; and Palka saw Judge last year in Triple-A. There is an appreciation among them — sometimes unspoken — of the rigors of professional baseball, a process akin to natural selection.

Dantzler was the most valuable player of the Class A short-season Northwest League in his first season with the Vancouver Canadians, but injuries and a dip in his performance persuaded him to retire after last season. He is working on his Master of Business Administration degree while training as a financial planner.

“Your dream, since you’re in Little League, is to play in the big leagues,” said Dantzler, 26, whose boyhood friend is another promising rookie, the Baltimore Orioles’ Trey Mancini. “That sticks with you. I was playing once or twice a week, and when you’re in it, you’re ready for a change. But I see Trey, I see Aaron — these are my buddies. You tell yourself, ‘I can do that.’ I have to remind myself what the reality of the situation was.”

Last month, Danztler was at Yankee Stadium, traipsing through the bleachers with his father. An inning later, Judge hit a ball that landed near where they had walked. Its distance was estimated at 496 feet, the longest in the major leagues this season.

“You hear major leaguers saying the same thing — you don’t see guys do what he can do,” said Aldrich, who had won the college derby the previous year, in 2011. “The ball comes off his bat different than everybody else.”

Judge, the only one in the 2012 derby who was from west of the Mississippi, was a relative mystery to the other players. Some had gotten a glimpse of him at the start of the Cape Cod League, but when they saw him up close — even though his warm personality disarmed them — they had an uneasy feeling about the contest.

When Horan shook hands with Judge, “it felt like I was shaking an outfielder’s mitt instead of somebody’s hand.” Added Dantzler, who is 5-10: “As soon as you see him, you’re like, ‘Oh, he’s the favorite, we’re competing for second place.’”

Katz jumped to an early lead, hitting seven homers in the first round. Horan hit five and Fisher and Judge hit four to advance to the next round. Katz increased his total to 12 in the second round, while Judge hit four more to advance with eight, along with Horan. Once in the finals, the totals reset to zero.

“Judge makes it look so easy,” Katz said. “It takes every ounce of my 5-9 frame to get it out of the park. I guess, looking back, I should have saved some energy.”

As Horan led in the final round, the atmosphere became more charged. When one player hit a long home run, others would wave a towel to feign cooling them off. Judge was signing autographs between swings during the finals. At one point, several players egged Judge on about flipping his cap backward, an ode to Ken Griffey Jr.

“All of us growing up, that was the beginning of when we fell in love with the game,” Fisher said of Griffey. “And that’s the hitter in baseball that we watched.”

With Judge down to his last out, he launched the next pitch out of the park. Then the next. And the next. With his final pitch — a money ball, worth two points if he hit it out — Judge looked over at the other hitters and turned his cap backward.

“He hit it about 460 feet,” Katz said.

Much has occurred in the past five years for these former college sluggers. Some careers have plateaued, some have fizzled and others are continuing an ascent. When they tune in Monday night, they all will be happy to see someone they consider a friend reach the top.

“It’s cool to be able to say I almost beat him,” Horan said. “It would have been cooler if I could have said I’d beaten the guy, but I was right next to him. That’s not bad.”