It wasn’t only the Yankees’ universe that got caught up in the two-month phenom that was Gary Sanchez.

“I’m in,” one opposing American League team executive said Monday. “I’m buying. I don’t think it’s a fluke. That’s a stupid pace he was on, but . . . with that swing, he should be a 30-home run guy, I would think.”

That swing produced historic numbers.

Despite a 2-for-30 slide to end the season, the 23-year-old Sanchez produced a .299/.376/.657 slash line, 20 homers and 42 RBIs in 53 games. Sanchez hit his 20th homer in his 51st career game, tying Wally Berger of the Boston Braves (1930) for reaching 20 career home runs the fastest. He hit nine home runs in a 10-game stretch and five in a subsequent four-game span.

Sanchez’s 20 homers tied him with Brian McCann (130 games) and Didi Gregorius (153 games) and left him one behind Starlin Castro, who hit 21 in 151 games. (Carlos Beltran hit 22 in 99 games for the Yankees before being traded to Texas on Aug. 1.)

“Those middle-of-the-order catcher bats . . . they’re hard to find,” said an executive from another competing AL club. “I like everything about his swing. He’s got power to all fields.”

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One scout from a National League club who watched his ascent through the Yankees’ minor-league system said Sanchez — who had a .282/.339/.468 slash line, 10 homers and 50 RBIs in 71 games with Triple-A Scranton/Wilkes-Barre this season — has developed as a hitter.

“He could always hit a fastball, knew he could hit a fastball and was looking fastball, trying to cheat and stuff like that,” the scout said of Sanchez’s performance in the minors. “That left him open to breaking balls. But the way he’s taking pitches [in the big leagues] and staying back, that type of approach, you can hit anything. And he did.”

Another NL scout said Sanchez’s “compact” swing stood out.

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“For a big guy, it’s not that long, sweepy swing you sometimes get,” the scout said, noting the trouble that fellow Yankees rookie Aaron Judge had (42 strikeouts in 84 at-bats). “Looks like he stays on it. And in BP, it looks like he’s got a little bit of a plan. Some guys in BP, it’s ‘slug BP’ and they’re just trying to hit home runs. He’s moving the ball around for a home run guy. He’s got some good habits going there.”

One AL scout said that impressive work at the plate aside, Sanchez needs some improvement behind it — obviously more so in receiving than throwing.

“He dropped a lot of balls, and that can really kill a pitching staff over [a full season], so I would say the glove needs some work,” he said.

Still, the scout added: “He’ll be fine. I wouldn’t be too worried. He seems like a worker, and he’s a lot better in that area [now] than in the minors.”

The day he was brought up to take over full-time catching duties from McCann, Sanchez said his work on defense was as important as his work with the bat.

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“It’s something I’m really proud of and believe is very important,” he said shortly after arriving Aug. 3.

After hitting homer No. 20, Sanchez said the quick success came as a bit of “a surprise,” but he did establish some lofty goals early on, though more in a general sense.

“I want to be one of the best out there in the game, that’s what I’m hoping for,” he said Aug. 3. “I’ve worked very hard to get here.”

His thoughts after his whirlwind two months?

“It was hard work,” Sanchez said. “I tried to give everything I had. We really wanted to make the playoffs, we couldn’t make the playoffs. What we need to do now is try to focus on next year. Come back ready.”

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Ready for what a full season might bring.

“It will be fun to have a full season,” Sanchez said, “and see what happens.”