The 9-2 rout underscored Syndergaard’s feud with the club’s hierarchy over its decision to pair him with catcher Wilson Ramos. He has made it clear he prefers Tomas Nido, who is less of an offensive threat than Ramos, but more skilled at framing strikes and handling Syndergaard’s sinker and two-seam fastball in the lower half of the strike zone.

The Mets listened to — then rejected — Syndergaard’s plea for his favorite catcher. The result wasn’t pretty: Forced to work with Ramos again, he was charged with four runs in five innings, including a three-run home run to the rookie Gavin Lux on a 3-2 curveball in the fourth inning that spun without downward break. It was Syndergaard’s worst pitch on an otherwise forgettable night.

That put deGrom in a make-or-break predicament the next night against Hyun-Jin Ryu, who has surpassed Kershaw as the Dodgers’ ace and was the N.L.’s starting pitcher in the All-Star Game. And just as the Mets had hoped, deGrom rose to the occasion: He matched Ryu inning for inning, zero for zero, averaging 100.2 miles per hour with his two-seam fastball, 93.7 m.p.h. with his slider and, most devastatingly, clocking his changeup at 92 m.p.h.

The three pitches together are poison to right-handed hitters: The two-seamer runs in on their hands. The slider sizzles over the outside corner. And the changeup, perfectly disguised as a fastball, arrives seven to eight miles an hour slower as it drops out of the strike zone. DeGrom threw it 12 times in the seventh inning alone; not once were the Dodgers able to square up on it.

“It looks like a fastball except that it’s not,” Bellinger said, shaking his head. “I mean, there’s not much you can do against stuff like that except give it your best shot. Obviously, the guy is a great pitcher; all you can do is try to compete.”

DeGrom says his changeup has always been his second-best pitch, set up by the blistering velocity of his fastball. Even on nights when the changeup feels out of sync, deGrom says, “I try to show it to hitters, just to keep it in the back of their minds. Sooner or later it comes around.”

Disarming hitters with those three weapons — fastball, slider, changeup — is precisely how Pedro Martinez dominated in the late 1990s. And like the Red Sox ace, deGrom has the advantage of long arms, “and a whiplike action in his delivery,” Manager Mickey Callaway said.