The 2019 Mets are more about the culture of Wilpon ownership and a roster forged by Brodie Van Wagenen — first as an agent, now as the general manager — than the managing of Mickey Callaway.

But the terms of engagement for this team have been understood for months. Neither the old owners nor the new GM were going anywhere. If the time came to try to defibrillate the clubhouse or change the narrative or provide a human shield for those most responsible, Callaway was being set up to be the fall guy this year after Sandy Alderson was last year, as Terry Collins was the year before, and so on and so on in the Mets’ relentless blame game.

And let’s face it, the time is approaching. Fast. And what feels inevitably. Callaway is managing Sunday against the Marlins. No one at this point should comfortably bet on Monday at Citi Field.

Near the outset of “Rounders,” Matt Damon’s Mike McDermott voices over: “Listen, here’s the thing. If you can’t spot the sucker in your first half hour at the table, then you are the sucker.”

The Mets entered a 13-game phase against the death spiral Nationals and International League Marlins ready to fatten up against inferior opponents. Except the Mets are the suckers. They must have missed the memo that they are inferior as well.

Jeff Wilpon called a meeting with Van Wagenen and Callaway before this phase began to send the real message of urgency and the subliminal message that next time something more drastic than a meeting would be undertaken. The best time for these kind of meetings is before games and series against weak competition and the Mets followed with two wins at home against Miami, then a series-opening triumph over Washington. They were back to .500 and believing Van Wagenen’s words that they were the team to beat in the NL East.

Now, they are back to presiding over the end of the Callaway administration. You speed up that clock by losing four in a row to these kind of opponents, notably two sleepwalks against the closest facsimile you will find to the 1962 Mets — that would be Derek Jeter’s Marlins.

Even now the Mets can con themselves that the first-place Phillies are just 5¹/₂ games away. But the record is 20-24 and the problems are historically familiar. The Mets are forever the piano that cannot get all 88 keys in tune — when they hit, they don’t pitch and when they pitch they don’t hit. They annually talk about syncing up. But what defines bad teams is that inability to either sync up or compensate well for what is not humming. They are, as always, a 44-key piano.

Would a good manager fix this? I doubt it. This begins at the top and works down. But it is becoming clearer that if a magician is needed to abracadabra away institutional, embedded Mets issues then Callaway has more in common with Art Howe than David Copperfield.

If he was ever going to succeed in New York, he probably needed to apprentice in a Kansas City or Milwaukee to just learn how to manage the nine innings, master that and then try to tackle the endemic problems of the Mets and the scope of doing the job in a huge baseball city.

Alderson’s final nail in his term was going 0-for-5 in 2017-18 free agency with Jay Bruce, Todd Frazier, Jose Reyes, Anthony Swarzak and Jason Vargas. But Callaway really makes it 0-for-6. And Van Wagenen hardly imported high-energy, high-performing self-starters that could compensate for what Callaway lacks in ability to jumper-cable life and belief into the roster.

But Callaway was always everyone’s cover. He is not this GM’s pick and so it was always an arranged marriage designed not to throw away the final two years on a three-year managerial contract. The Mets wanted to believe they saw signs of improvement in Callaway as last year progressed. But upgrading from abysmal to bad is seen as improvement only by an organization that fights delusion as surely as the rest of the NL East.

Maybe the Mets win Sunday and that stays a job execution. But it is very hard to stop negative momentum in this town and for this team.

These Mets have been incapable of rallying for their manager against the Nationals and Marlins, when it has been understood around the club that Callaway has as much job security as Keon Broxton. So it feels like we are just talking about a day, some part of a losing streak now or in the near future before bench coach Jim Riggelman is elevated and the latest blah blah blah about new voices and different directions are burped.

This is just marginally Mickey Callaway’s fault, but he has not expressed the skills to be good enough at this job to do it well and overcome all the malfeasance around him. So unless he morphs into a combination of David Copperfield and John McGraw — and quick — his less-than-magical run is about to go poof.