NEW YORK -- The pitch that Mariano Rivera refers to as "a gift from God" inexplicably appeared one afternoon in June 1997, as the reliever played catch with a teammate in front of the Yankees' dugout. Each toss darted with wicked movement, and what would be recognized as the most lethal cut fastball in history had been born.
With that magical offering, the regal Rivera destroyed countless bats across big league infields, celebrating championships and eventually standing alone as the all-time saves leader. Time was the only remaining obstacle to his selection to the National Baseball Hall of Fame, a call that came Tuesday as Rivera was unanimously selected to the Class of 2019.
Set to be joined by Roy Halladay, Edgar Martinez and Mike Mussina at next summer's ceremonies on July 21 in Cooperstown, N.Y., Rivera appeared on all 425 ballots cast by eligible members of the Baseball Writers' Association of America, making him the first player to be unanimously elected. Class of 2016 member Ken Griffey Jr. previously held the high mark, getting 99.32 percent of the vote.
"I was just happy to pitch in the big leagues and play for the New York Yankees -- as many championships as I could do it," Rivera said. "After my career, I was thinking: Did I have a good shot to be a Hall of Famer? This was just beyond my imagination. This is the pinnacle of every athlete or every player that played the game of baseball. Just to be considered a Hall of Famer is an honor, but being unanimous is just amazing to me."
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Widely considered the greatest relief pitcher ever, Rivera spent his entire career with the Yankees, from 1995-2013, compiling 652 saves while finishing 952 games, both Major League records. His 2.21 ERA and 1.00 WHIP are the lowest in the live-ball era among qualified pitchers.
A 13-time All-Star, Rivera was at his finest when the stakes were the highest. He secured 42 saves and owned a 0.70 ERA in the postseason, celebrating five World Series championships and seven American League pennants. More men have walked on the moon (12) than have scored an earned run off Rivera in the postseason (11).
"Mariano was a fierce competitor and a humble champion, which has made him such a beloved baseball legend," said Yankees managing general partner Hal Steinbrenner. "Success and stardom never changed Mariano, and his respect for the game, the pinstripes and for his teammates and opponents alike makes this day such a celebration of his legacy. There will be many more great and talented relief pitchers, but there will never be another like him."
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Video: Mariano Rivera unanimously elected to Hall of Fame
The son of a commercial fisherman, Rivera was born in Panama and raised in the modest village of Puerto Caimito, signing with the Yankees as an amateur free agent in 1990 for a $3,000 bonus. Rivera made his professional debut that summer as a starting pitcher, arriving in the Majors in 1995 before finding his destiny in the bullpen.
"I remember where I came from and I never forget where I came from," said Rivera, who joins Rod Carew as the only Panamanian Hall of Famers. "I've always been a person that has respect for everybody, and being humble was something that I learned and appreciate back home. My humble beginnings, we didn't have much."
As the setup man for closer John Wetteland, Rivera enjoyed a dominant '96 season that helped give birth to a dynasty, as the Yankees won four of the next five World Series titles. Rivera took over as the full-time closer in 1997, the same year that the cutter first zipped out of his right hand while tossing with reliever Ramiro Mendoza across the turf of Tiger Stadium.
Summoned to the bullpen, pitching coach Mel Stottlemyre observed Rivera's discovery, at first tinkering with his grip and arm angle in an effort to restore the ball's straight motion. After a couple of weeks, the Yankees realized how special Rivera's new pitch was, boring in on left-handed hitters and away from righties. It was a gift from the heavens, one that Rivera kept until the end.
"When I start thinking about it and put in perspective how I was able to dominate with one pitch, all I have to say is that I'm grateful to the Lord," Rivera said. "I have to thank the Lord for that, because He was just amazing. I can't think that such a thing like that can be possible, but it was possible with me. The Lord used me in amazing ways."
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The unflappable Rivera displayed his smooth, repeatable motion for the final outs of the 1998, 1999, 2000 and 2009 World Series, the only pitcher to throw the last pitches of more than two titles.
"He is absolutely the best," former teammate Paul O'Neill said. "I have said it many times -- we would never have had the run in the '90s without Mo. I don't know many people I respect more than Mariano, because of who he is and how he stayed who he was, even while being the best ever."
Said former teammate Andy Pettitte: "This is a pretty obvious statement, but I wouldn't want anyone else closing out a game that I started."
Video: Mariano Rivera reacts to being congratulated by Jeter
Even in rare defeats, Rivera stood apart: after permitting a Series-deciding hit to the D-backs' Luis Gonzalez in the 2001 Fall Classic, Rivera calmly sat at his locker until the final questions were answered.
"Mariano is a rare, once-in-a-lifetime pitcher, and the greatest closer to ever play the game of baseball," former teammate Jorge Posada said. "There was such a humility and grace to the way he did his job -- day after day and year after year. I'm so proud of everything he has accomplished, and I'm ecstatic that he and his family can celebrate this ultimate honor."
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Video: Rivera reacts to his unanimous election to the HOF
For a generation of fans, Rivera's entry signified dominance and -- more often than not -- victory. Early in 1999, Rivera's emergence from the right-field bullpen at Yankee Stadium began to be accompanied by the strains of Metallica's "Enter Sandman," a heavy-metal song that clashed with Rivera's Christian music preferences.
Yet the image of Rivera jogging to the mound, No. 42 stitched upon his back, made for tremendous theater. Exit light, enter night. Rivera never complained about the song, embracing the effusive reaction it produced from packed houses in The Bronx. Beloved for his consistency, Rivera saved at least 25 games in 15 consecutive seasons and posted a sub-2.00 ERA 11 times.
"I had the best seat in the house from center field, watching him pitch," Bernie Williams said. "It was mind-boggling to see him literally just mow down hitters. Mariano would cause more broken bats in one inning than most starters had in an entire game. If we had a lead in the ninth inning, the game was over."
At age 42, Rivera had privately decided that 2012 would be his final season, a plan that was altered that May when he tore his right anterior cruciate ligament while tracking a fly ball during batting practice in Kansas City. Rivera vowed that he was "not going out like this," and his subsequent return in 2013 sparked a league-wide celebration.
• Cue the 'Sandman': Mariano, Metallica song synonymous
Video: Metallica congratulates Rivera on HOF election
Each road trip prompted outpourings of love and respect for the hurler, who reciprocated by personally thanking fans and employees at each stop. Rivera spent time with groundskeepers, soldiers and students while receiving numerous gifts and donations for his foundation.
"No matter how big a star he became, he never failed to carry himself with unerring professionalism and class," general manager Brian Cashman said. "Mo was always someone who I could point to and say, 'That's what a Yankee should be like.'"
The Yankees held a fine celebration in late September, escorting Rivera to his rightful place in Monument Park while retiring his No. 42 for all time. Raising his palms with gratitude toward the Stadium's most distant seats on a sun-splashed afternoon, Rivera acknowledged the rhythmic chanting of his first name, and that his place among the legends was secure.
Now, as the first unanimous Hall of Famer, it is even more so.
"The Lord blessed me and opened a door for me to become the New York Yankees' closer," Rivera said. "We had 25 tremendous players, nine on the field and the others waiting on the bench to take action. I can never say that I accomplished [this on my own], because it would be impossible. We accomplished through all 25 players, and that is the beauty about it."
Bryan Hoch has covered the Yankees for MLB.com since 2007. Follow him on Twitter @bryanhoch and on Facebook.