Besides life on his fastball and bite on his slider, you know what was missing with Matt Harvey?

Compassion.

That probably says more about Harvey’s now-done tenure with the Mets than just about anything.

There was no empathy from a teammate or member of management for Harvey’s plight. They wanted him to rebound and do well, but that was about the Mets and their own selfishness for success.

Think about when CC Sabathia went through lost effectiveness on the field and a battle with alcohol off of it in the 2013-15 span. The Yankees organization bled for him. The clubhouse and front office were pulling for the lefty to work through his problems on the mound and in life. It spoke to who Sabathia had been as a teammate — giving, team-oriented, convivial, supportive. He was feeling the return, a baseball quid pro quo.

Harvey never enjoyed such traction within the Mets’ walls. He put some great pitching in the bank, but not much goodwill.

A scout said something recently that stuck with me: “Mantle and Namath carried on off the field, but they were beloved in their clubhouses. They included their teammates in the good times and were great teammates. So, their teammates would go to war for them. I wonder if anyone has ever told Matt Harvey that.”

For no one around the Mets was going to war for Harvey. Does Harvey have enough self-awareness to realize what that says about him? What it might mean for him having a next chapter in his career? How it poisoned the now-concluded chapter?

Think about his most recent off-the-field brouhaha: He went to a restaurant opening in Beverly Hills while the team was in San Diego with a game the next night. This had all the trappings of sounding and seeming bad. But was it actually bad?

It seemed bad because he was about two hours from the team hotel and doing something beautiful people do — going to a restaurant opening in Beverly Hills. But what, for example, if I had told you David Robertson went to a restaurant opening on a Thursday night in Philadelphia (two hours from New York) and pitched out of the bullpen on Friday night. Would you even care?

Maybe you would ask what time he got to bed. But while a Yankee, Robertson has handled himself in a high-end professional way and, thus, would get the benefit of doubt all around.

Since Harvey did not speak about his event — by the way, he has no goodwill with reporters, either — we don’t know when he returned. Heck, he might have been in bed by midnight. But even if it was 4 a.m., there is still plenty of time to get eight hours of sleep. Baseball players don’t have regular jobs. And I will let you in on a little secret: these are young, rich guys and they go out plenty during the season, especially on the road.

The difference is that Matt Harvey is Matt Harvey, which is to say he has behaved so poorly and built no strong alliances in any way with folks around his now former team. So when he went to a restaurant opening in Beverly Hills, the worst scenarios were implied. No one thinks he was just a reliever who might or might not get used the next day, so is he never supposed to go out and enjoy himself?

Thus, I think he was treated unfairly in this episode and yet I also think he was treated exactly as he had earned. You can’t be the presence he had been throughout his Mets tenure and expect to get the most positive spin. He had no connective tissue in his clubhouse or with this franchise. Sandy Alderson’s wry dismissiveness rather than disappointment spoke to how little Harvey had in the bank — there was no attempt to try to alibi for him and yet also no energy expended on even being that mad. Harvey just wasn’t worth even anger any longer, as he had been when he was a gifted arm attached to an overprivileged body.

Now, the arm appears gone. All that was left was a divorce date. That came Friday, the Mets designating for assignment a former first-round pick and king of the city. The Mets obviously stopped believing Harvey could come back and haunt them this year or they just stopped caring. Harvey had that effect — the Mets just stopped caring.

At the moment of exit, Matt Harvey was just a bad major league reliever without much support around him. He was an island of ineffectiveness. His fall should have educed empathy. That it did not speaks louder about Harvey’s time as a Met than any 98 mph fastball ever did.