MLB

Post-Rivera era almost unthinkable for Yankees

TAMPA — For the Yankees, it is The Day After Tomorrow scenario. It is the horror show lurking somewhere in the future.

Maybe Mariano Rivera is indestructible and will not break down or walk away until we have President Bieber. But — believe it or not — someone else will someday be the closer of the Yankees. And if you do not like how the search for Andy Pettitte’s replacement is going, think about filling those shoes.

“Let’s not,” Jorge Posada said. “He’s almost irreplaceable. He is a freak of nature.”

Rivera is the best closer ever. But to leave it with just a platitude is to not fully understand his meaning. For that you have to understand that in the large majority of places, closers bring agita, tension, distrust. Faith is lost in the stands and in the clubhouse.

Think about, say, life with the Mets in the recent past. Think about what Shea Stadium and Citi Field have felt like when a John Franco or Armando Benitez or Francisco Rodriguez enters. A sense of dread — not euphoria — engulfs the place. Those guys were all accomplished closers, and yet, when they had a couple of rough outings, doubt crept into the clubhouse. There is an unspoken concern about if late leads can really be held.

It brings a poisonous atmosphere familiar around the sport, but one that the Yankees have not had to deal with for 15 years. When “Enter Sandman” plays, Yankee Stadium believes that is the opening chords to a successful close. No doubts. And when Rivera blows a save, it is not death around the Yankees. The feeling, actually, is “when can we get the ball to Mo again?”

This is what happens when you are the greatest. But also when you are drama-free. Rivera hardly fits the caricature of a closer. No fire-breathing, no theatrics. He is the brilliant singer who can mesmerize without gimmicks; just microphone and talent; just ball and talent.

He is without the pathologies of the closer on the tightrope. He hardly walks anyone, hardly gives up homers. If you want to beat Mo Rivera, you have to get three singles to score a run before he gets three outs. Good luck. His career batting average-against is .210.

During Rivera’s tenure, the Yankees have brandished elite offenses and usually high-end starting pitching. Yet, emotionally, the team has played the game backward: Get a lead, get the ball to Mo. He has been security blanket and safety net. “Close to perfect,” according to Posada.

“He is the most consistent,” Posada added. “He has the most longevity. He has the same routine over and over and over. The focus never changes. He’s actually tough to explain if you don’t see it every day. I have never seen anyone else like it in the whole sport at any position. I just have never seen anyone as good as Mariano Rivera.”

From the look of the recent past, why think the good times are going to end? His 1.64 ERA over the past three years is not only the best in the majors (minimum 150 games). But it is the best three-year run of his career. And it comes in his age 38-40 seasons. He has lost some velocity and gained savvy and aura to more than compensate.

Still, he did turn 41 in November, and is the fifth-oldest active player. His innings totals have dropped each of the past six seasons in recognition of his age, and his strikeout rate fell to a career-low 6.75 per nine innings last year.

“There is a question how much longer he can do this physically,” Joe Girardi said. “He is not 32 anymore.”

And if the physical doesn’t get him, will he go the way of Pettitte, who could still pitch at a high level, but lost zeal for the sport. Rivera did not arrive to camp until yesterday because one of his children was sick. He described his youngest son as attached to his hip crying for daddy not to leave. However, armed with a new two-year contract, Rivera described his passion as fully intact.

For now Rivera will be on his usual low-throw output spring, saving those valuable bullets for the regular season. Obviously, at 41, there are fewer left. Tick. Tick. Tick. It can’t be avoided

The Day After Tomorrow is coming.

joel.sherman@nypost.com