Rivera rides signature pitch to No. 600

Hitters dread it, opposing managers scheme to avoid it, GMs spend millions trying acquire a reasonable facsimile of it. To that, Mariano Rivera has said, simply, good luck. Since 1997, he’s owned the patent on the pitch no one can duplicate.

With 600 career saves, the latest coming Tuesday night in a 3-2 victory at Seattle, Rivera’s place in the record book is now permanently affixed, as if he didn’t already belong there. There’s endless arithmetic that explains the Yankees’ ninth-inning dominance for parts of the last three decades, but even advanced metrics can’t quantify the mystery of Rivera’s personal nuclear weapon — specifically, the cutter.

There’s no answer to why hitters can’t solve it and why no one’s been able to copy it after all these years.

The pitch’s genius is in its simplicity: there are no tricks or gimmicks in the delivery or execution. Instead, Rivera prevails with the same, maddening calculus: Throw the cutter, make it break too late to detect, feather it over a corner and then defy anyone to make good contact.

“It’s like a buzz-saw,” is what Chipper Jones once said. “It just eats you up, especially if you’re a left-handed hitter. You know it’s coming, but that doesn’t really help you much.”

The question is how, without the element of surprise, does Rivera keep making hitters look so bad? Better yet, how is it that younger, stronger pitchers can’t make their own cutters behave similarly?

Major leaguer hurlers aren’t embarrassed to tell Rivera they’re stumped. They ask for tips, and he’s happy to dispense it. Even the Yankees’ rivals are allowed to visit Mount Olympus. But there’s a saying among pitchers who spend a few minutes with the Yankee closer, thinking they’ve cracked the code. Throwing a Rivera-type cutter is like juggling — it looks easy until you try it yourself.

It can’t be done without an exceptionally long, loose arm and a flexible wrist. Rivera is blessed with both of these assets, evidenced by his extraordinary front-to-back shoulder rotation from the moment he begins his wind-up until the instant the ball is released.

“It’s what you would teach a Little Leaguer, frame by frame,” said former Yankee right-hander David Cone, now a broadcaster for the YES Network. “Mariano’s arm slot is the same every pitch. To me, that’s what sets him apart is being able to repeat what’s already perfect mechanics. No one else does that.”

But even Rivera’s ability to clone himself, pitch by pitch, wouldn’t be enough were it not for the tremendous spin-rate on the cutter. Such is the gift of Rivera’s genes — a wrist that’s so loose and fingers that are so long they’re able to touch his wrist.

That’s what creates the illusion of a fastball until the very last moment. Because Rivera can make his cutter spin so furiously, the rotation delivers the ball in a straight line practically to the front edge of the plate. Only then, after a hitter has begun his swing, does the cutter reveal its lateral signature. It’s why, as David Ortiz described, “the pitch that you swing at is a fastball. The one you make contact with is the cutter. It’s unbelievable.”

Here’s the other factor that distinguishes Rivera’s cutter from those of his peers’. Even though conventional instruction says finger pressure must be applied to make a ball move or break, Rivera believes in no such thing. Instead, he grips the seams as if throwing a four-seam fastball, slides his thumb a half-inch to the right and thus creates an imbalance in his hand. The sphere’s left half is more than halfway exposed.

All Rivera has to do now is throw the fastball. No manipulating the fingers, no twisting or snapping of the wrist. “Just throw it,” Rivera says. “Throw it and trust it.”

That’s no easy task, as pitchers who attempt to copy Rivera usually end up “around” the ball — that is, with their fingers or wrist to the side, effecting more of a slurve than anything else.

“The thing is, it’s actually an easy pitch to control, which is why so many pitchers fall in love with it,” said Rick Peterson, former pitching coach to the A’s, Mets and Brewers. “It’s easy to control the way it’s easy to harness the way a Frisbee breaks. It’s almost easier than flinging it straight. But it comes at a cost.”

Too many improperly thrown cutters can erode velocity. Even the great Rivera has seen his radar-gun readings drop into the low 90s as he neared his 40th birthday. Now at 41, there are days when Rivera barely touches 91 mph, which might explain why hitters’ contact ratio against him has climbed incrementally since 2008.

Of course, there will someday be an end to Rivera’s dominance. The cutter will leak enough velocity to strip it of its stealth quality, like a dog whistle that comes down an octave.

Rivera is secure enough to acknowledge the decline of his skills, as subtle as it might seem today. “When the day comes that I can no longer do this at the level I want,” he said, “then I will go home the very next day.”

Until then, Rivera’s continues the surreal journey and, with it, setting records that won’t be broken. Forget about anyone else reaching 600 saves; that’s safe forever. Only Trevor Hoffman stands in front of him, with 601 saves. The next two active save leaders are Francisco Cordero (322) and Jason Isringhausen (300).

Even more permanent is Rivera’s legacy in the postseason, where his career 0.71 ERA over 139-2/3 innings represents a stand-alone miracle. “That’s where the best hitters are concentrating and focusing the most,” said CC Sabathia. “And they still can’t hit Mo.”

Still can’t hit the cutter, to be more precise. It’s left a million broken bats in its wake, not to mention a generation of sluggers who’ve muttered the same tortured question on the way back to the dugout: “How am I supposed to hit that?”