Adam Haseley’s phone would not stop buzzing.

It was Sept. 4, the three-month anniversary of his ahead-of-schedule major-league debut, and he had just made the catch of his life. Eighth inning. Cincinnati. Phillies trailing by one run. Haseley tracked Freddy Galvis’ long drive to the wall in right-center field, timed his leap, and snatched a surefire home run out of mid-air. It was an instant “SportsCenter” top-10 play, a classic web gem.

And it earned Haseley endless ridicule.

"No one was even talking about the catch," Haseley said the other day, laughing through the phone. "A lot of the texts I got, everyone was just making fun of me about the response."

Well, it was priceless. After coming down with the ball, Haseley matter-of-factly took a few steps from the warning track onto the grass, flipped the ball from his glove to his left hand, and tossed it back to the infield as though it was all no big deal.

It's one thing to "act like you've been there before," as Vince Lombardi famously directed his players after they scored a touchdown. It's another to be emotionless.

“I was just shocked that it happened,” Haseley said. “It was just a natural response for myself.”

Indeed, it was vintage Haseley. He stood calmly on second base after slashing a go-ahead RBI double for his first big-league hit on June 5 in San Diego. He gently tossed his helmet after reaching on an error to end a 15-inning game on Sept. 27 at Citizens Bank Park. And he hardly popped champagne last month when the Phillies gave him the inside track on winning the center-field job in spring training.

But Haseley also has a confession. Beneath that layer of cool, he felt mostly like a slack-jawed novice throughout his rookie season.

“From June on, I was definitely in a state of awe, kind of shock, and just super appreciative and thankful just to be in Philly and playing with the big-league club,” Haseley said in a half-hour interview. “I was out there sometimes and I was like, ‘This is insane.’”

A year ago, after all, Haseley was preparing for spring training as a non-roster invitee to major-league camp. A former first-round pick and the eighth overall selection in the 2017 draft, he was hopeful of eventually reaching the big leagues. But given that he started the season at double-A Reading -- and the Phillies had Andrew McCutchen in left field, Odubel Herrera in center, and eventually Bryce Harper in right -- he had a long way to go.

By the first week of June, though, two-thirds of that outfield was gone. Herrera got arrested on May 27 on charges of assaulting his girlfriend in an Atlantic City casino hotel. Seven days later, McCutchen tore a ligament in his left knee and needed season-ending surgery.

Haseley, despite playing only six games at triple-A Lehigh Valley, was rushed to the majors.

“In a perfect world, he would have spent more time in the minor leagues,” general manager Matt Klentak said recently. “He had some ups and downs. It wasn’t a perfect rookie season. But I think he gives a real good at-bat. I think when you look at the body of work over three months that he was in the big leagues that’s a pretty impressive rookie season. I think there’s reason for optimism that he’ll be better than that. But that was a pretty good rookie season.”

Good enough, at least, for Klentak to declare last month that “Haseley’s going to be our regular center fielder,” an intention that was further strengthened last week when the Phillies designated Herrera for assignment and outrighted him to triple A.

Haseley, 23, started 59 of the final 101 games last season, including 36 in center field. He batted .266 and slugged .396 with 14 doubles, five homers, four steals, and a .324 on-base percentage. On average, National League center fielders batted .254, slugged .420, and reached base at a .321 clip last year.

“He’s got a very good idea of the strike zone,” Klentak said. “He had that as an amateur, and he started to show it at the big-league level. I know his strikeout totals weren’t great, but if you watch his at-bats, I think you can see he has that still. And I think as he starts to become more comfortable at this level, we’ll start to see that more and more.”

Haseley said he began to feel more like he belonged in the majors by August, pointing to a three-game series in Arizona in which he went 5-for-11 with two doubles as a sign that he “could play at that level at a normal, calm pace.” And although he followed with a 5-for-36, 18-strikeout skid, he batted .304 with eight doubles, two homers and an .807 OPS over his final 28 games.

Wherever possible, the Phillies tried to protect Haseley from early failure. As a left-handed hitter, he rarely started against lefties, even though he actually had better numbers against lefties than righties in double A. Several veteran players took a liking to Haseley’s quiet, understated style. Jay Bruce worked closely with him before games on drills that were designed to keep his swing short.

"It was a matter of just trusting myself and trusting in the decision to have me in Philadelphia with that team," Haseley said. "I trusted that they believed in me and I believed in myself. I had a peace and confidence, with how the last stretch of the season went, that I had set myself up for an opportunity in the spring to be on the team and to make a difference."

Haseley said his confidence didn’t waver even after the Phillies fired manager Gabe Kapler and replaced him with Joe Girardi. He had a brief introductory conversation with Girardi and came away thinking he would be in position to win the center-field job in spring training.

With a franchise-record payroll that is bumping up against the $208 million luxury-tax threshold, the Phillies are counting on it. Haseley, third-base prospect Alec Bohm, and prized pitcher Spencer Howard represent the organization’s next wave of inexpensive homegrown players. It’s essential for them to graduate to the big leagues.

The time for wide-eyed awe is over.

“My mindset has been that I don’t want to just go into spring training and feel things out and see where it lands," Haseley said. "Now it’s like, ‘OK, this is an opportunity in front of me. What am I going to do with it? How am I going to approach my work in a way that’s going to set me up in a position to succeed at that level?' I don’t think they’re looking at me and hoping that I’m just not in shock of playing with them. They’re depending on me to do my job. I need to hold up my end now, too.

“I don’t just want to be the guy that’s young and in awe all the time. I think it’s a great perspective to always have to be appreciative of the opportunity. But there’s also that sense of, ‘OK, here’s the opportunity. Go get it.’”