PHILADELPHIA — In different circumstances, this would have been the kind of pitching performance that left the Mets convinced the top of their playoff rotation will be just fine.

That might still be the case, just not this year.

Nolan McLean faced a formidable Phillies lineup Sunday afternoon and dominated.

It was just the latest strong performance for the rookie — and maybe his best this season — in leading the Mets’ 6-1 victory at Citizens Bank Park.

The right-hander struck out 10 over six shutout innings, allowing only two hits and two walks.

The Mets won the series rubber game, giving them a shred of momentum to open the post-All-Star break.

But the reality is, the Mets are 16 games below .500.

McLean had a sixth straight start of pitching at least six innings, the longest such streak this season by a Mets pitcher.

Along the way, his ERA dropped to 3.34 — the lowest it has been since May 19.

“It’s a lot like a lot of rookie seasons for really good pitchers,” interim manager Andy Green said. “He’s shown flashes of greatness and then he’s had to labor through other parts of the season. But for us I don’t think there’s any way to look at it other than really positive. The stuff is really good.

“We want him to pitch at the top of the rotation, so the challenge is always going to be out in front of him to continue to move up and get better. But I think when you are talking about rookies sitting in the three-and-change ERA range, it’s impressive and we still think you can be more impressive.”

Francisco Lindor’s two-run homer in the first inning got his team started.

The Mets assembled a two-out rally, with Bo Bichette drawing a walk against Alan Rangel before Lindor connected for his sixth homer this season.

Luis Torrens’ RBI double in the second, following Brett Baty’s leadoff single, extended the Mets’ lead to 3-0.

The Mets loaded the bases later in the inning and received an RBI single from Lindor and Carson Benge’s sacrifice fly for a 5-0 lead.

Juan Soto delivered an RBI single in the sixth that buried the Phillies in a 6-0 hole.

Torrens and A.J. Ewing each singled in the inning.

Alec Bohm homered against A.J. Minter in the seventh to give the Phillies their only run.