You know that baseball cliché about seeing something for the first time just about every time you come to the ballpark? Thursday in Queens, cliché was reality.

Because for the first time in Jacob deGrom’s 160 starts as a major leaguer, the Mets scored four runs in the first inning. Four. Runs. In. The. First. Inning.

This must have been overwhelming for a pitcher whose team had given him an average of 3.71 runs in his first 20 starts this season and 3.49 last year and had failed to score as many as four times in 31 of his 52 starts over the last two years.

Christmas in July for likely the best pitcher on the planet.

“Every time I go out there, I try to think of it as a 0-0 baseball game,” deGrom, who has much experience at that, said after the Mets’ tidy 4-0 victory over San Diego. “The goal is to put up zeroes.”

Mission thus accomplished for the second consecutive outing, seven shutout innings in this one after seven of the same in San Francisco last Friday, when he did indeed depart a scoreless game that became a 10-inning, 1-0 defeat. DeGrom has a shutout streak of 17 innings stretching back to July 14 following this performance in which he repeatedly unleashed hellacious sliders that turned the Padres’ bats into plowshares.

“It’s a daunting weapon. When it’s like today it’s probably the best slider in baseball,” said Mickey Callaway, whose team is 7-5 since the All-Star break. “Jacob has the knack to do that. That’s who he is.”

And in this one, the Mets were who they haven’t been most of this season; heck, most of the last three seasons. They not only caught every ball they should have, they even made the plays they probably wouldn’t have on most given days.

Callaway before the game talked about how his team “relies a lot on run prevention.” Starting pitching aside — and even the exalted rotation has been less than advertised, pitching to only the eighth-best ERA in the National League — that pronouncement might have created confusion or giggles given the manager’s or the general manager’s penchant for disregarding the importance of the defense’s impact on run prevention.

For the Mets not only have failed every eye test, they entered Thursday’s game last in the NL and next-to-last in MLB in Baseball Reference’s total fielding runs (-47) and last in MLB in FanGraph’s defensive ranking (-40.6). That’s what happens when you put players in positions where their chance of success is not optimum. (Footnote. See: Smith, Dominic, left field.)

And nowhere have the Mets been more wanting than up-the-middle, with Wilson Ramos struggling behind the plate, Amed Rosario undependable at shortstop and corner outfielder Michael Conforto shifted to center, where he has unsurprisingly most often looked like a corner outfielder.

But Thursday, Conforto was in right while Juan Lagares, who Once Upon a Time in Flushing evoked flashbacks of a young Willie Mays in the field, was in center. And Rosario turned in the type of sparking performance that might discourage the Mets from trying the lifelong shortstop in center field to make room for 20-year-old Andres Gimenez, the club’s next (alleged) rising star.

“I feel no type of pressure,” Rosario said through a translator. “I feel really confident because of all the work I have been doing.”

Callaway said Rosario had been working studiously with coach Gary DiSarcina on his crossovers and anticipation.

“He’s improved dramatically,” the manager said.

Rosario made his first dandy play in the third inning, going backhand to snare Luis Urias’ hard one-hopper before throwing him out. He made another beauty on Urias in the seventh, laying out to grab a shot toward the middle to get an inning-ending force out at second base.

“I’m excited and happy about it,” Rosario said. “We have been working on early preparation, so I’m always ready before the pitcher winds up, and on angles. It shows the hard work is finally paying off.”

Lagares, whose .185/.253/.265 slash line has limited him to three starts this month, made one eye-opening play, going from shallow right-center to deep left-center to haul in Urias’ drive with one on and two out in the fifth. It was routine for Lagares. It would not have been routine for Conforto.

“I had great defense today,” said deGrom, who allowed four hits, all singles, while striking out nine and walking one. “That helped.”

The Mets pitched. The Mets also caught the ball. You do see something new every day.