CHICAGO — The wheels came off for Mickey Callaway and the Mets Sunday at Wrigley Field in so many ways.

First, the beleaguered manager stuck with reliever Seth Lugo for much too long. Lugo’s 42nd pitch, a poor slider, was deposited into the right-field bleachers by Javier Baez for a one-out, three-run home run in the eighth inning that lifted the Cubs to a 5-3 win over the Mets, their most excruciating loss of the year.

The Mets can’t blame Dave Eiland for this one. Management tried to pin the bullpen woes on Eiland, who was fired Thursday.

Callaway never got his closer up, never elected to bring Edwin Diaz into the game at any point and was agitated by the questions in his post-game press conference.

He said he didn’t want to bring Diaz in for a five-out save or even a three-out hold and then get the final two outs with another reliever. Diaz, who has thrown just 12 pitches in eight days, said he would have been fine with a five-out save, a four-out save or any work at all, but he never got the call.

Then in the clubhouse after Callaway had been interviewed in his office, a frustrated Callaway walked past reporters and Tim Healey of Newsday said to the manager: “See you tomorrow, Mickey.’’

That set off Callaway. He yelled, “Don’t be a smart-ass motherf—–.’’

Callaway went to the food area briefly, came back and yelled, “Get the motherf—– out of here. We don’t need that bullsh–.’’

Jason Vargas, whose locker was directly across from where Healey was standing, said the reporter was staring at him as Vargas stared him down.

“I’ll knock you the f–k out, bro,” Vargas said, rushing across the room.

That is when Noah Syndergaard and Carlos Gomez intervened. The reporter left the clubhouse.

This was dysfunction in the clubhouse and confusion on the field, just a terrible line of decision-making by Callaway. Double-switches were made as well in which red-hot Jeff McNeil, who did not start against lefty Cole Hamels, never got into the game and Todd Frazier, who also had been swinging a hot bat, was double-switched out.

I wrote the day Eiland was fired that Callaway would be next to go if the ship continued to sink.

Brodie Van Wagenen doubled down on Callaway at the time. Sunday’s was not a pleasant scene and Van Wagenen left the clubhouse immediately after the game ended and missed the fireworks.

There is a lot of tension surrounding Callaway and the club.

There really was no excuse not to go to Diaz. Lugo was clearly spent because he came in for Jacob deGrom in the seventh. DeGrom had an issue with a callus on his landing foot. Callaway told reporters there was nothing physically wrong with deGrom, that he was just “gassed,” so his credibility is taking a hit on several fronts, and that never plays well in a clubhouse.

The Mets were looking to win their first road series since April 1-3 in Miami, but it was not to be as they dropped to 37-41.

Reporters heavily questioned Callaway about his bullpen usage.

“We are not going to use him for five outs,” Callaway said of Diaz. “You guys keep asking, but my answer is going to stay the same.”

Asked if the plan that Diaz can’t be used for five outs or even four should be revisited, an irritated Callaway said, “No, just because you think so? Absolutely not. We have a very good plan, we know what we are doing and we are going to stick to it.”

The plan is so good, the Mets are four games under .500 and have not won a road series in 81 days.

The walls and the losses are closing in on Callaway. His team can’t get over the hump and now the Mets will face a struggling Phillies squad.

In the words of former Mets GM Sandy Alderson, what happened Sunday was “bad optics.”

Pressure and losing affects players, managers and teams in different ways. It is not easy working for the Wilpons.

Mickey Callaway is struggling to stay above water. Another Mets season is going down the drain and Callaway is the manager of this mess.

But for how much longer?