ST . LOUIS — Paging Dr. Callaway. Paging Dr. Eiland.

Not only do Mickey Callaway and pitching coach Dave Eiland have to have advanced degrees in pitching mechanics for the Mets, they also have to be baseball psychiatrists.

Callaway admitted as much after the Mets’ terrible 9-1 loss to the Cardinals Wednesday night at Busch Stadium.

To get to the root of Steven Matz’s pitching woes, they are going to also have to get inside the lefty’s head and figure out why he falls off the rails when a problem arises.

Such was the case in this game as Matz’s wild throw to first base on opposing pitcher Michael Wacha’s bunt in the third inning sent the southpaw into a tailspin.

By the time the dust settled, Matz was out of the game after 3 ¹/₃ innings, his ERA had risen to 4.98, he tied his career-high allowing seven runs and in three of his five starts Matz has gone four innings or less.

This all comes one night after Matt Harvey made a shaky bullpen appearance. Harvey, the starter formerly known as the Dark Knight, is so steamed he told reporters Wednesday night there was “No chance. Zero chance,’’ that he would talk about his situation.

Asked why he was not talking, Harvey said, “I don’t f—— want to.’’

Callaway has told Harvey that he and Eiland will continue to work with him to try to fix his problems. They will not quit on him, but you have to wonder what will become of Harvey.

Same goes for Matz. He has to learn to let things go on the mound and not dwell on mistakes that crush him.

“One little throw to first kind of unraveled things and he just couldn’t get it back,’’ Callaway said of Matz. “It’s a mentality of letting go of what just happened and continuing to know you are in a good spot in the game because you pitched two really good innings and just because you threw a ball away at first doesn’t mean things are going bad. If you let it, it will. We have tons of ways to help him. It’s going to take some time.’’

Like the song says: Let it go.

“I think we need to sit down and figure out how we can help him in that regard,’’ Callaway said.

Remember the dream of the Mets five aces. Remember what Jacob deGrom, Noah Syndergaard, Harvey, Matz and Zack Wheeler were supposed to become. Earlier this month they finally all pitched in succession for the first time, hope was still alive.

That hand has folded, at this point the Mets will take a pair of aces in Syndergaard and deGrom and whoever else can emerge from the group. No job is really safe after the top two.

Matz is not able to put the brakes on when things begin to spin out of control. He fights himself on the mound and before you know it he and the Mets are in a deep hole.

Sure, the Mets have had 10 comeback wins, but their run differential is just plus-nine. They are making the most of every run to be 15-7.

Callaway and Eiland are working with heads as much as arms.

“Absolutely, we all know they have the stuff,’’ Callaway said. “The thing that separates [Max] Scherzer from anybody else is his mentality. Not his stuff. He has great stuff but so do all of these guys. It’s the mentality that is going to make you a consistent pitcher.

“I don’t deal with expectations. I deal with what I see.’’

Pitching reality.

Matz is confused and frustrated.

“The game sped up on me out there,’’ Matz said. “Sometimes it gets away from me real quick.’’

That is the root of the problem. Matz allowed the game to get away from him because the throw on Wacha’s bunt got away from him.

Now that Callaway and Eiland have seen this happen they will have to find a way to fix the mental approach for Matz.

Matz has to learn how to let it go on the mound and in his mind.