The Mets are the perfect illustration of the warp speed at which professional sports operates and in which credit expires almost immediately.

Their 2015 trip to the World Series might as well have happened in 1915, for all of its staying power. Instead of forming the foundation of an era of excellence, that season quickly has come to represent an oasis in the expansive desert of despair through which the franchise is doomed to wander.

One by one, they have gone down or gone elsewhere. Just seven players — Wilmer Flores, Yoenis Cespedes, Michael Conforto, Jeurys Familia, Jacob deGrom, Noah Syndergaard and Saturday’s starting and losing pitcher, Steven Matz — had survived attrition and purge and remained on the active roster entering the 7-6 loss to the Yankees at the Stadium.

Now it is six.

The Mets began unpacking their depleted cupboard of veterans 10 days before the July 31 non-waiver trade deadline by sending Familia, the closest thing to a big-time closer in Queens since Billy Wagner about a decade before him, to Oakland for a couple of middling prospects and a pocketful of international slot money.

Trading Familia, always available to take the ball but never quite so dependable as his save totals might indicate, was inevitable. There is no more useless appendage on a bad baseball team than a closer. And though it might be unfair to suggest that the headless front office settled in what the club got in return for the 28-year-old pending free agent, it sure doesn’t appear as if a bounty is coming this way.

We’d love to tell you what management’s spin on this was, but no one other than manager Mickey Callaway was available to talk to the media. There are three heads — John Ricco, J.P. Ricciardi and Omar Minaya — in charge of the operation, but no voice to address this or the burgeoning issue regarding Cespedes’ health.

When people talk about the Mets Way, this is probably what they mean. Oh, wait. No one ever talks about the Mets Way. This is probably why.

Callaway gave Familia, whose 123 career saves place him third on the franchise’s all-time list behind Armando Benitez (160) and John Franco (276), his due in his postgame briefing.

“The A’s are lucky to have a quality guy and pitcher like Familia,” the manager said. “He’s done a great job for this organization but I understand that it’s necessary at this point to try and strengthen the team for the future.”

Familia had his warts. He served a 15-game sentence at the start of 2017 for violating MLB’s domestic abuse policy. That does leave an indelible stain on his record. But in the clubhouse, he was always a friendly face. And on the mound, he was the cherry on top of the Matt Harvey-deGrom-Syndergaard-Matz sundae that was so good while it lasted, but melted all too quickly.

He was a key contributor on the giddy ride to the Series and then, a year later, nailed down a franchise-record and league-leading 51 saves as the Mets earned a wild-card berth with a late charge down the stretch. During that season of sunshine, Familia converted 52 consecutive save opportunities from late July 2015 through mid-July 2016. Regular-season save opportunities, that is.

Because even as such an integral part of the team’s success, Familia blew Game 1 of the World Series by serving up a game-tying home run to Alex Gordon in the bottom of the ninth inning of a game the Mets lost in 14. Then, undermined by a Daniel Murphy muff at second base, he blew a save opportunity in Game 4, unable to hold a 3-2 lead in the eighth in an eventual 5-3 defeat.

Game 5, well, another one, though if Lucas Duda had just been able to make an accurate throw from first base to the plate in the ninth inning, perhaps the fate of the franchise would have changed. But no. Familia could not hold the precarious lead he inherited from Harvey and the Mets ultimately fell off the ledge in 12 innings.

Happenstance.

It happens.

But it happened to Familia again the following postseason. Having entered the wild-card game against the Giants to start the ninth inning with the score 0-0, Familia surrendered a three-run home run to a fellow named Conor Gillaspie and that was that. The Mets were done; done for the season and done for the foreseeable future.

Familia hit some heights here. He was a large part of it for Terry Collins. But with his trade to Oakland, he epitomizes what the Mets were and are:

So near, so far and now gone.