MLB's milestone players: 10,000th-19,000th By JohnW53 on Apr 17, 2021, 6:58am CDT + 20,000th player since the the first game played in the National Association, the first true league. Through Thursday, the count stood at 19,944. This is the second of 2 posts looking at the players who were the 1,000th, 2,000th, etc., to appear in a big league game. This post covers the 10,000th through 19,000th. .......... Andy Kosco, pinch hitter, age 23, for Minnesota Twins, American League Kosco became No. 10,000 exactly 94 years, 3 months and 9 days after the first 18 players squared off on May 4, 1871. That is 34,434 days. He pinch hit for pitcher Garry Roggenburk with 1 out and nobody on in the eighth inning at Cleveland, with the Twins behind, 3-1.