Mariano Rivera is the greatest pitcher to ever play baseball. Not the greatest closer ever — the greatest pitcher. Ever. I believe this, without a shred of doubt. Hundreds of millions of people have “seen” Mariano Rivera pitch on television on the sports highlight shows, but of his 1,100 official appearances on the mound during regular season or the playoffs, perhaps half were at home during a game when Rivera was called in from the bullpen to maintain a tie or to preserve a lead and close the night out. In those instances, perhaps only a few million people actually saw him do his work live, in person, in the flesh, in the Bronx, late at night, when the whole world seemed to stop for a moment.

I am one of those lucky few million people.

You have to be in the outfield bleachers to truly feel his presence. It’s late at night. It’s October in New York. It’s playoff baseball. It gets dark around 5pm, and it gets a lot colder by game time. The game is close, very tightly played. Base-runners run conservatively. As the game goes on, the starting pitchers lose their edge. Batters start choking up. A blooper here, a sacrifice there, and all of a sudden, a go-ahead run is manufactured out of thin air. It could have easily been the visiting team. With the game in the balance, there was only one thing for the manager to do: Pick up the phone, call the bullpen, and tell the greatest pitcher in the history of baseball to start warming up.

Rivera hangs out in the outfield bullpen all day. He just sits there. Sometimes he stretches. He laughs with his teammates. When the game gets late, like the night I remember, and he’s called up to start warming up, the bleachers go crazy. Everyone stops and yells to their neighbors in the stands “Mo is up.” He starts playing catch with the bullpen catcher, and after a few throws, affixes his cleats to the mound, strikes a pose to the plate, and then in his classic mechanics, arches his right downward and behind his body from his glove, turns his shoulder with effortless grace, and applies the most nasty torque to a baseball the game has ever witnessed.

It’s worth noting the unusual signature of Rivera’s key pitch: The cut fastball. It is a pitch that, if you can believe it, gains speed as it approaches the plate, disrupting the batter’s timing. To a right-hander, already statistically unlikely to get a hit from the right-handed Rivera, the “cutter” approaches the plate and moves up and away from his hands; to the left-hander, it creeps toward the handle of his bat, often shattering it upon impact. Despite all the science and technology in professional sports, and the fact that every batter knew exactly what Rivera was going to throw, there were no match for his physics. In his remarkable 19-year career, some stats to ponder: (1) he struck out more batters than innings pitched, but gave up less hits than innings pitched; (2) for every 9 innings he pitched, he’d on average give up only 2.21 earned runs; (3) he only walked 286 batters; and (4) opposing batters had a 21.1% chance of getting a hit against him per at-bat.

Back to the game…when it was time for Rivera to grace the stage, the lights dimmed a bit at Yankee Stadium. People stopped what they were doing. The early, deep chords of Metallica’s “Enter Sandman” reverberated through the Stadium. I get goosebumps just thinking about it. The crowd would start to cheer and chant. In the concrete and wood bleachers, you could feel the energy pass through all the fans huddled shoulder to shoulder, and through your feet. I am not a religious person, but it felt like a religious experience to me, the presence of someone otherworldly, who commanded everyone’s attention, and brought order to an otherwise chaotic existence.

The bullpen doors in the outfield wall would open. Rivera would start to walk toward them. He’d take a few small steps through over the threshold and on the warning track, and then he’d start jogging (with purpose) through the outfield toward the mound, his theme song getting louder along with the crowd’s excitement. For those few minutes, even the players would transform into fans. I’d like to think they knew they were part of something special, that this one player was truly a cut above everyone else. In an era of impurity in baseball, gimmicks, baseball camps and clinics, cheating and a rejection of classics, Rivera’s God-given talent cast everything else to irrelevance.

Once the game resumed, and fans and players went back into character, Rivera usually closed out the game, tuning out the noise and focusing his mental acuity on just one thing: pitching. He often just faced only 3-4 batters per outing. It was like clockwork. By the time Mariano made his first pitch, the game was often over. Sure, despite his successes, he was front-and-center to two big collapses, where he could’ve save the game in big playoff games. Even-keeled during the many highs, Rivera was always the mark of class during a tough defeat, as if to say, nonchalantly, with a hint of zen, that sometimes in baseball, as in life, you win, and sometimes, you don’t. It is all part of God’s plan.

I don’t follow baseball as much I used to nowadays. There are a lot of reasons as to why, but they don’t matter. What matters is that I was lucky enough to watch enough baseball to know there was one player who was simply better than everyone else. He wasn’t perfect, but he was about as close as they come to perfection. Tonight is a night I’ve been dreading for a few years now. I thought Mo would retire a few years ago. Last year, in 2012, when he tore his knee in a freak accident, I thought he was done, but he rehabbed and returned for this season, his numbers after injury on par with his level of excellence.

When Rivera walks off the field Thursday night at the Stadium, an important era in baseball will end. Not only is Rivera the greatest pitcher to ever pitch in baseball, he was the most valuable player the Yankees had during that time. Derek Jeter may get all the attention, but I’d bet even he would say there’s no one more consistently valuable than Mariano. My own feelings are mixed. I am grateful to have seen him pitch many times, to experience the energy he channeled and shared with the fans. I wonder if I’ll ever see someone play baseball like he did again. I doubt it. That’s what makes it sad. After tonight, he will be gone, perhaps never to be seen again, to only live in the memories of millions of people who intuitively understand they may never see a player as great ever again.