The secret is out: Michael Conforto’s sweet left-handed swing is not only among baseball’s most aesthetically pleasing, but also the most efficient.

Only 75 games into his major league career, the 23-year-old Mets outfielder seems to have it all figured out, with only the height of Conforto’s ceiling still in question.

“Is he a young Barry Bonds, without as much power?” a talent evaluator who has watched Conforto extensively asked rhetorically Thursday. “But he might show more power as time goes on.”

Conforto’s .338/.429/.615 slash line with three homers and 13 RBIs in 19 games might partly be a product of the weak competition the Mets have faced over the past two weeks. Nevertheless, Conforto has emerged as the most consistent force in a lineup that boasts Yoenis Cespedes and the NL’s co-leader in home runs entering Thursday, Neil Walker.

In his team’s 5-2 victory over the Reds on Wednesday that completed the series sweep — the Mets will take a six-game winning streak into Friday’s game against the Giants at Citi Field — Conforto delivered the knockout punch with a two-run double in the sixth, after going hitless in his first three at-bats.

“You have to keep yourself on an even keel and not ride the roller coaster,” Conforto said. “Just try to go up there with the same mentality every single time and get a good pitch to hit, and I ended up coming through on the fourth try.”

Conforto’s surge has corresponded with his move to No. 3 in the lineup. According to a club source, the discussion about moving Conforto to third began in spring training. It didn’t come to fruition until after manager Terry Collins watched his lineup scuffle over the first eight games of the season.

“He’s a classic No. 3 hitter,” said former Mets first baseman Keith Hernandez, a club broadcaster for SNY. “The question is, how good will he be?

“He is a natural hitter — the first natural hitter for the Mets since [John] Olerud. Emphasis on ‘natural.’ ”

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An AL scout who watched Conforto play a recent stretch of games was impressed by the player’s maturity.

“Nothing seems to faze him,” the scout said. “I would play him every day, with maybe the exception of when you are facing Clayton Kershaw or a few other guys.

“He’s a good-looking young hitter. He’s got a good idea of the strike zone. For skipping Triple-A, it was a pretty advanced approach when you saw him.”

Conforto’s 1.050 OPS with runners in scoring position would indicate he’s more than capable of carrying a lineup. And Conforto carries the mindset that hitting with runners in scoring position is a skill.

“You have to be up in those situations, maybe there is some luck there, you can’t get the job done every time, but I think it’s a skill,” Conforto said. “You see guys who over the course of their careers they have better numbers than others in those situations, so I think some guys handle those pressure situations better than others.”

Conforto’s offseason routine might have served as the perfect preparation for those big situations in a game.

“I worked on being able to stay back and put an offspeed pitch the other way, and I put myself through those situations,” Conforto said.

“You can put your mind in that state, just by imagining you’re up there with a runner on second, a runner on third, with less than two outs. You can have those reps in the offseason, and it’s something I worked on in the offseason and it’s definitely paying off.”