Mets first baseman Pete Alonso, left, and Yankees catcher Gary...

Mets first baseman Pete Alonso, left, and Yankees catcher Gary Sanchez. Credit: Jim McIsaac

Similarities between a pair of homegrown New York sluggers have invited natural comparisons this season, but it might not be the two you think.

One is in the Bronx, the other in Queens. One already made his mark in the Home Run Derby, the other will try to do so next week. One captured the baseball world’s attention during a recent torrid summer, the other is doing so now.

Rookie first baseman Pete Alonso is the Met. His Yankees counterpart is not Aaron Judge, according to a coach who knows all parties well.

“The comparison is Gary Sanchez,” said Tom Slater, the Mets’ assistant hitting coach, citing his former pupil and the American League All-Star starter at catcher. “They’re similar hitters. They both hit the ball really hard all the time, they both use the whole field, and more importantly than their power, they’re both really good hitters.

“Both guys do a great job of watching the game and making adjustments throughout the game. Really intelligent, really pay attention to the game and really good hitters who also have the ability to hit the ball out of the park. To me, that’s the more applicable comparison.”

Slater is uniquely positioned as an expert on this subject. For nine seasons — 2009-17 — he worked in Yankees player development. In 2010, when Sanchez was a raw but supremely talented catcher getting his first taste of professional baseball, Slater was his manager with the Yankees’ Gulf Coast League team. They also worked together in 2013-14, when Slater was the roving minor-league hitting instructor.

When the Mets visited the Dodgers in May and got a visit from Southern California resident David Wright, the former Mets captain and current front-office special adviser posed a question to Slater: Whom did Alonso remind him of?

It wasn’t a New York-centric query, but Slater kept it in the boroughs and didn’t hesitate in answering: Sanchez.

“His ability to use the whole field as a 17-year-old and to make in-game adjustments and to two-strike hit and everything, I was blown away watching Gary Sanchez at 17 years old in rookie ball,” Slater said. “Much in the same way, it’s really impressive watching Pete in his rookie year — using the whole field, two-strike hitting and everything he can do.”

Sanchez finished second in the AL Rookie of the Year voting in 2016, when he hit 20 homers in only 53 games; Alonso is a favorite for the NL award this year. When Sanchez competed in the Home Run Derby in 2017 — eventually won by Judge — he ousted defending champ Giancarlo Stanton in the first round at Marlins Park; Alonso will go for the crown Monday in Cleveland, a day before making his first All-Star appearance.

With all of Alonso’s success — the 28 homers, the 64 RBIs, the .999 OPS — he has become a fan favorite and frequently is cited by manager Mickey Callaway as a leader in the clubhouse. That is uncommon attention and status for a first-year player.

“He’s a mature young man,” Slater said. “He works hard, he puts in his time in his prep — studying the opposing pitchers and in his cage work and his batting practice. Everything. It’s everything.’’

For Slater, any Subway Series — including the two-gamer at Citi Field on Tuesday and Wednesday — is a time for handshakes and hellos. He keeps tabs on his other onetime mentees, which includes most any hitter who has come through the Yankees’ system in recent years: Judge, Sanchez, Gleyber Torres, Clint Frazier and the injured Miguel Andujar and Greg Bird.

“You pay attention to the guys you know and you’re happy for the successes they have,” he said. “You just hope they don’t have too many against your team.”