MLB

No predicting arm woes, but that’s little solace to Harvey, Mets

There are injuries that make perfect sense, we can see them: Joe Theismann’s shin snapping like a twig on Monday Night Football; part of Tim Krumrie’s leg going one way and the rest going the other in Super Bowl XXII; Kevin Ware rising to contest a 3-point jumper, then falling in a sickening heap of bone and ligament.

There are injuries that we can understand, because we know sports can be dangerous: The sprinter who blows out his hamstring; the quarterback whose brain is concussed by a vicious sack; the running back who shreds his ACL; the baseball player who breaks a rib thanks to an inside fastball.

But a pitcher’s arm …

“Everyone thinks good mechanics prevent arm injury,” tweeted former pitcher Mark Mulder, who himself saw his career derailed by his million-dollar left arm. “Doesn’t matter, people. Either you get lucky or you don’t.”

Matt Harvey officially falls into that second category now, after spending so much of the past year in that rare place athletes always crave: at the top of their profession, on top of the world, young and invulnerable and bulletproof.

Until you slide into an MRI tube one morning at the Hospital for Special Surgery, your arm achy but not wracked with pain, safe in your innocence and your naivete and your belief the doctors will find a little tendinitis, maybe suggest skipping a start or two.

Until you slide out of that tube.

And the news comes back as something else.

“Obviously,” Harvey said yesterday, “this was the last thing I was expecting when I went in this morning.”

It was certainly the last thing the Mets needed to hear, the progressive roll call of a cruel vocabulary. Two awful words: partial tear. Three awful words: Ulnar collateral ligament. Four awful words: Tommy John surgery possible.

“Not good news, obviously,” Mets GM Sandy Alderson said.

Not for the Mets, who have spent five years trying to spin their way out of a baseball black hole, and not for Alderson, who has pledged for months that 2014 would mark a grand return to contention. Not for Mets fans, who must never feel more jinxed than they do right now, this instant, watching this jewel of a prospect damaged like this. And certainly not for Harvey, who learned the terrible truth that all it takes for your life to turn upside down is the look on a doctor’s face when it turns from interested to concerned.

“You never know,” Harvey said, his voice softer than we’ve heard before, his face bearing exactly the look you would expect from a 24-year-old who has just stared down his immediate future and seen two options: scary and terrifying.

“This can be fixed,” said his manager, Terry Collins, but Collins has been around the game long enough to know that no matter how well Harvey’s recovery goes it will never be the same around him, around his starts, even if the radar gun insists otherwise, even if his stuff eventually returns.

Every pitch he throws from this day forward will contain a warning label, whether he has the surgery or not, because once the mysteries of a pitching arm reveal themselves a pitcher is never the same. Mulder is right. Justin Verlander throws just as hard; he’s never had a setback like this. Mark Prior’s mechanics were perfect enough to make a pitching coach weep: His career ended before it ever started.

Harvey said it: You never know.

There will be a rush to attach blame for this, of course, because it is so difficult to reconcile this pitcher, this career, hitting this road block. There were a few games Harvey was asked to work an inning after 100 pitches; did that do it? There was the All-Star start, when he was clearly amped up; did that do it? He had been experiencing forearm discomfort; was that the workaday pain all pitchers deal with, or was it a warning signal?

Did that do it?

Or is it as simple as this, a word of advice Collins once heard from Dr. Frank Jobe — inventor of Tommy John surgery — when Collins was working for the Dodgers and Jobe was asked how you keep pitchers’ arms healthy: “No matter how hard you try, if they’re gonna break, they’re gonna break.”

Matt Harvey broke yesterday. He can be fixed. But even if he’s the same, or better, it will never be the same, not really. Every time he lets go a fastball, every time he breaks off a slider, the question will shadow the ball like a vapor trail: Is that it? Is that the one? Either you get lucky or you don’t.

Yesterday, Matt Harvey’s luck ran out. If you can explain why, you will make yourself very, very rich.

michael.vaccaro@nypost.com