LOS ANGELES — Jason Vargas was everything the Mets could have wanted Thursday night in keeping his team competitive and swallowing innings to rest a depleted bullpen.

But it was the left-hander’s misfortune to face the National League’s early Cy Young award front-runner, who was performing at peak level for the Dodgers.

In a matchup that on paper screamed “no contest,” Vargas and the Mets were only a step behind in a 2-0 loss at Dodger Stadium.

Dodgers ace Hyun-Jin Ryu was brilliant over 7 ²/₃ shutout innings, in which he allowed four hits and lowered his major league-best earned run average to 1.48. Kenley Jansen recorded the final out in the eighth before pitching a scoreless ninth for the save.

In the best performance of his Mets career, Vargas allowed one run on six hits over seven innings. Vargas’ ERA dropped from 5.22 to 4.46, moving him ahead of Noah Syndergaard (4.90) and Zack Wheeler (4.63) in the Mets’ rotation.

Vargas’ longest previous outing this season was 5 ¹/₃ innings against the Reds on April 30. In his two starts since returning from the injured list, Vargas has allowed one run over 12 innings for a 0.75 ERA.

“I think just effectively pitching down,” Vargas said, when asked about his success.

With suspicions the Dodgers were stealing signs in the series, Vargas said he “worked out a couple of issues with [runners] on second base.”

But the veteran lefty downplayed the matter.

“I had a pretty good idea, based on what I could see from video,” Vargas said. “It was something I would take advantage of, too, so it was something we had to combat.”

The Mets (27-29) departed Southern California with three losses in the four-game series, but knew it probably should have been a split — at worst. A night earlier, Edwin Diaz allowed four runs in the ninth inning in a 9-8 loss, after the Mets had blasted four home runs.

“We don’t want to go 1-3 in a series, but we did put ourselves in a position to do better than that,” manager Mickey Callaway said.

The Mets will open a three-game series Friday night at Arizona with Wheeler on the mound. After a strong start to the season, the Diamondbacks have faded and are a game below .500.

Hector Santiago, following Vargas, pitched the eighth and allowed a run on Kiké Hernandez’s single after David Freese had doubled.

Pete Alonso’s double leading off the seventh gave the Mets a pulse — they had only two singles to that point — but Ryu retired Todd Frazier, Carlos Gomez and Adeiny Hechavarria in succession to keep the Dodgers’ lead at 1-0.

“[Ryu] was commanding all four pitches,” J.D. Davis said. “It was tough, backdooring that curveball, commanding that changeup, that fastball, that cutter in. It was tough to read the ball on him and all of his pitches were coming out of the same arm slot.”

After encountering plenty of early traffic, Vargas got rolling in the middle innings, facing only one batter over the minimum from the fourth through the seventh, allowing Callaway to avoid using too much of his overworked bullpen.

Max Muncy’s RBI double in the first gave the Dodgers a 1-0 lead. Chris Taylor led off the game for Los Angeles by hitting a sinking line drive that skipped past Davis in left as he attempted to make a diving catch. Taylor raced to a triple before Muncy hit a shot to center.

But Vargas escaped further trouble. That included pitching around the dangerous Cody Bellinger for a one-out walk. A subsequent walk to Alex Verdugo loaded the bases with two outs before Russell Martin was retired.

The Mets had their best early chance against Ryu in the second, when Frazier walked and Gomez singled, but the lefty retired Hechavarria and struck out Tomas Nido to conclude the inning.

“[Ryu] is like a left-handed Greg Maddux out there,” Callaway said. “He did a heck of a job.”