NEW YORK -- This will be Dellin Betances' 21st Subway Series -- fourth as a player, the rest as a New Yorker. This would have been T.J. Rivera's first as a player, but his number in that second category is the same as that of Betances, as it is for any baseball fan their age who grew up in New York City.
Betances, the Yankees reliever, is from Manhattan, and went to high school in Brooklyn. Rivera, the Mets infielder currently on the disabled list with a partial tear of the ulnar collateral ligament in his right elbow, is from the Bronx. Both were 9 years old when the series became an annual event in 1997, the perfect age to lose yourself in the cross-city drama it sparks each summer.
"The atmosphere was always great and very evenly split. Depending on where you lived, it felt like everyone was half-Yankees, half-Mets," Betances said. "When you are a kid, you are all watching, fighting for bragging rights."
Millions of kids grew up in this city doing just that. 
Counting Betances and Rivera, seven players born and raised within New York's city limits have participated in the current iteration of the annual Subway Series, which began when Interleague Play was introduced in 1997. The others are John Franco (Brooklyn), Allen Watson (Queens), Bobby Bonilla (Bronx), Mike Baxter (Queens) and Steve Karsay (Queens).
Five others -- think Steven Matz, John Flaherty and John Valentin -- played, but have nearby suburban roots. Five more, including Alex Rodriguez, were born in New York but raised in other places.
Baxter became the first player to watch the modern Subway Series as a New York kid and then play in it in 2013. This year, Betances and Rivera could have become the first two native New Yorkers to face one another in the series, which would have been an intriguing matchup for several reasons.
First, Betances is a strikeout pitcher who can struggle with his control, while Rivera is a high-contact hitter who walks infrequently. Second, Betances has been a star in New York since he was a towering teenager, a sandlot-circuit darling, one of the city's best prospects of the century. Rivera was a non-prospect who had to prove himself at three colleges and countless Minor League towns.

And third, a meeting between the two wouldn't just link teams and boroughs. It wouldn't just represent a shared celebration of the city's baseball culture, on it's biggest shared stage. It would also have marked a sequel of sorts more than a decade in the making.
Betances and Rivera faced one another on the high-school circuit, in 2006, when Betances was a senior at Grand Street Campus and Rivera was a junior at Lehman High.
To give an idea of their differences in their baseball status at the time: Betances does not remember pitching against Rivera in high school. But Rivera certainly remembers facing Betances.
Everyone knew Betances, because of his size, his fastball, and the fact that he'd likely be a millionaire soon. At 18 years old, Betances was 6-foot-8, and throwing in the low 90s.
"Not only was he the Empire State Building standing on the mound, intimidating opposing batters," Melvin Martinez, Betances' coach at Grand Street, wrote in an email to MLB.com. "But he still owns the longest home run ever hit on our field, estimated at 475 feet!"
Rivera, meanwhile, was growing, anonymously, into one of the city's best line-drive hitters. He played on elite scout teams but was not given the prospect pedigree of teammates Pedro Alvarez, Pedro Beato or Johnny Monell, all of whom made the Majors. Rivera eventually left Lehman without a college scholarship, while Betances' commitment to Vanderbilt, an elite national program, dropped his Draft stock that spring. He ended up signing with the Yankees as an eighth-round Draft pick for a bonus worth $1 million, which was more commensurate with being a late first-round pick at the time.
Betances intimidates Major League hitters now. Back then, he was the same height, pitching against high school hitters. Rivera remembers facing Betances only once, in a non-league game during Easter week at Lehman's home field.
"But he was just a freak," Rivera continued. "I was just jealous. We were all jealous."
Grand Street and Lehman were two of the city's most competitive public school programs, but because they played in different boroughs, they met only in non-conference contests or playoffs.
"Our mound was always higher and closer than most," Rivera said. "It was not a fun at-bat."
After all this time, Rivera wants another chance. Maybe next year, if his elbow is healthy, in this Subway Series that has now linked New Yorkers from all sides of the city for two decades.
"I didn't get a hit," Rivera said. "That was the only time I ever faced him. He shot up, and I never saw him again."