NEW YORK — Mets president of baseball operations David Stearns revealed that the team will be “active” in the trade market for a relief pitcher on Monday.

If they can’t pull off a deal for bullpen arms, then they’ll “begin to think” about promoting some of their top prospects from within, namely starters Brandon Sproat and Nolan McLean.

“I think for any prospect, it’s a combination of where they are in their developmental progression and where the team need is,” Stearns said. “Both those guys, I think, over the last three weeks, have taken meaningful steps forward in their development, and I’m excited to see where it goes from there.

“If there is a need, I think either of those guys could be ready over the next couple months.”

After a rough start to the season in Triple-A, Sproat has taken a massive step forward in his progression. He hasn’t allowed a run in his last four starts, striking out 27 batters in 23 innings.

This season, Sproat has a 4.34 ERA, down from 5.95 on June 22, with 70 strikeouts over 85 innings in 19 starts.

Promoted to Triple-A on May 6, McLean has been near-perfect in the minor league’s highest level.

Take away his last start, where he allowed six runs (five earned) in 3 2/3 innings, and McLean has a 2.52 ERA (17 ER in 60 2/3 innings) with 65 strikeouts.

The “challenge” with going this route, Stearns warns, is that it’s difficult to stretch a pitcher back out once he’s been shortened.

“We can certainly reverse ourselves over the off season,” Stearns said, “but once we shorten someone up to give them a chance to be a member of our pen, really tough to build them back up if you need them as a starter.”