Before, it was Diana Ross and the Supremes, as well as Gladys Knight and the Pips, and now it’s Matt Harvey and the Mets. Please welcome baseball’s newest diva.

As the team from Queens embarks on its first postseason berth since 2006, their star pitching performer may not be on the October stage as long as his fans, his manager or general manager would prefer.

The roots of this disconnect stretch back to spring training, when Harvey was returning to the mound after missing an entire year due to Tommy John Surgery. While the Mets were heavily involved in monitoring the progress of their young pitching stud, there had been no official mention of an innings restriction.

Leave it to agent Scott Boras to drop the hammer earlier this month. He noted a “hard cap” of 180 innings for Harvey – who at the time had tallied 166.1– before he shuts it down for good. A thought that had simmered around the Mets front office for five months (but had never materialized) officially blew up.

Once Boras lit the fuse, Harvey was scheduled to speak to the media the next day. Instead of putting out the fire, he fanned the flames – regularly telling reporters that he was focused on his next start against Washington.

With that, he singlehandedly placed his reputation and image on a tee for the public and New York media members alike to take a hefty swing.

Whether it was planned immediately after the backlash or well in advance, Harvey put his name to a Players’ Tribune article the next day to pronounce his commitment to pitching in the postseason.

But there’s still plenty of grey area in the Dark Knight’s immediate future. Harvey is scheduled for two more regular season starts before a likely Division Series outing. How many starts and how many far he can go in postseason remains up in the air.

Boras may have started up the controversy, playing puppet master in this saga. But it’s Matt who should really be pulling the strings, as Boras works for the player and not the other way around.

Harvey could have easily put a stop to those doubting his dedication to the team. Better yet, he could have prevented it from ever being generated.

There’s nothing wrong with a pitcher wanting to be cautious for the sake of his health and income. There is fault, however, in not giving your employer fair warning of what may come – especially when you made proclamations about being the workhorse into October and scoffed at the idea of a six-man rotation earlier in the year (an idea specifically designed to better monitor his output).

Boras obviously got into Harvey’s head, and Matt is mostly going along with it while remaining ambiguous with the media. Mao didn’t do this good of a job at brainwashing.

What Harvey is failing to realize is that character and importance to his ball club in critical moments can also lead to lucrative contracts down the road – just as much as a healthy and effective right arm.

GM Sandy Alderson and manager Terry Collins were blindsided by the imposed 180 innings mark for 2015. Thus, they are placed in a very precarious position: abide by the advice of Boras and Dr. James Andrews or continue on their own plan and disdain said advice, which would potentially hinder these relationships down the road.

Rest assured, his arm won’t explode into a thousand pieces if he throws 182, 194 or even (God forbid) 200. There’s no solid scientific evidence that exceeding a certain arbitrary standard such as inning count could be a reason for further damage.

Nonetheless, the odometer went up on Sunday night. But once Harvey put up five stress-free shutout frames against the Yankees (176.2 total), it was time to put the bubble wrap back on the fragile limb and ego of a starter with still much to prove.

Upon Collins reducing him to a workload that most little leaguers consider tame, Harvey was seen in the dugout mystified and upset about this decision. Someone hand him an Oscar.

Naturally, a fan base longing for the winning ways they’re currently experiencing isn’t happy that the supposed savior would rather save for his future than take advantage of what’s in front of him presently. Collins, who helplessly has his hands tied, is just as displeased.

Matt Harvey embraced the alluring attention that New York has to offer. But now he’s getting more than he’d prefer. Only a sustained and successful playoff showing will prevent the Big Apple from turning against him.