NEW YORK -- It was subtle, perhaps even imperceptible to the untrained eye. But as Todd Frazier watched the early moments of Thursday’s game against the Reds at Citi Field, he noticed a different glint in Noah Syndergaard's eye. Stepping into the batter’s box, several Reds gave Syndergaard nods of respect. In turn, Syndergaard roundly ignored each of them, glowering from his perch atop the mound.

It was, as manager Mickey Callaway posited afterward, as if Syndergaard took a long look at his 1-3 record and 6.35 ERA and said, “Enough’s enough.” He then spent the next two hours and 10 minutes single-handedly beating the Reds, becoming the seventh pitcher in Major League history to homer and pitch a 1-0 shutout in the same game.

• Arms That Hammer Sweepstakes

“He was a one-man wrecking crew out there today,” first baseman Pete Alonso said.

Added Frazier: “He got his swag back a little bit.”

That mission began with a strikeout of Jesse Winker, a newborn villain in Flushing who was later ejected for arguing balls and strikes. It ended with Syndergaard’s hardest pitch of the day: a 99.5 mph fastball to freeze Yasiel Puig. In between, he mixed together five pitch types in delivering one of the most dominant outings of his career. Syndergaard struck out 10, walked just one and allowed four hits.

He also received close to zero offensive support from his teammates, which might have mattered if not for Syndergaard’s other accomplishment. Facing Reds starter Tyler Mahle to lead off the third, he crushed his sixth career homer to the opposite field, matching Tom Seaver for second place on the franchise list for pitchers and moving within one of record-holder Dwight Gooden. Mets starters have hit four home runs this season, tying the franchise record with 131 games yet to play.

“It wasn’t a very competitive pitch, and he made me pay for it,” Mahle said.

Syndergaard needed no further inspiration than that. From the third through ninth innings, he retired 17 of 18 batters, erasing the only man to reach base on a double play. When he struck out Puig to end things, Syndergaard became the first pitcher to toss a 1-0 shutout via his own home run since the Dodgers’ Bob Welch in 1983. Only five others have done it, none since 1971.

“It’s got to be one of the rarest things in baseball,” Callaway said.

Indeed, it is more than three times rarer than a perfect game -- in the context of baseball history, a fun statistical nugget. In the context of the Mets’ season, it was heaven-sent. The Mets entered Thursday’s play trying to salvage a series split without their closer, Edwin Díaz, who had appeared in four of their previous five games, and another valuable reliever, Seth Lugo, who had pitched in three of four. Two of the Mets’ other top five relievers were on the injured list, with the club smack in the middle of a stretch of 13 games in 13 days. Had Syndergaard completed anything less than nine innings, Callaway said, “We don’t know how we get through the rest of the game.”

Nearly as alarming was the status of the rotation, which until recently had not lived up to its billing as one of baseball’s best. All five Mets starters struggled at various points in April, in a pattern that began changing only last week. Wednesday, reigning National League Cy Young Award winner Jacob deGrom delivered seven shutout innings. Syndergaard took notice. A day later, he offered his own signature outing -- providing not only a win, but hope that this sort of thing can continue.

“I think things are just now starting to click with us, and we’re really going to hit a run,” Syndergaard said. “I think this is where it starts to take a turn.”