He was drafted by the New York Mets in the 12th round of the 2013 Major League Baseball draft. After signing, McNeil made his professional debut that summer with the Kingsport Mets, hitting.329 in 47 games. He played 2014 with the Savannah Sand Gnats and St. Lucie Mets, hitting.292 with three home runs, 51 RBIs, and 17 stolen bases in 117 games, and 2015 with St. Lucie and Binghamton Mets, slashing.308/.369/.377 with one home run, 40 RBIs, and 16 stolen bases in 123 games. After the 2015 season, he played in the Arizona Fall League. In 2016, McNeil began using an unorthodox knobless bat given to him by Mets minor league hitting coordinator Lamar Johnson; he thenceforth began using knobless bats exclusively. He played in only 51 games combined in 2016 and 2017 with Binghamton, St. Lucie and Las Vegas 51s due to numerous injuries. McNeil started 2018 with the Binghamton Rumble Ponies and was promoted to Las Vegas during the season.
New York Mets
McNeil was promoted to the Major Leagues on July 24, 2018. He recorded his first Major League hit that night at Citi Field against Phil Hughes of the San Diego Padres on the first pitch he saw. He hit his first Major League home run off Tanner Roark of the Washington Nationals on July 31. For the season with the Mets, he batted.329/.381/.471 in 225 at bats. He led all MLB hitters in batting average against right-handers, at.345. McNeil received one vote in the 2018 National League Rookie of the Year Award polling, placing him in a three-way tie for sixth place with Harrison Bader and Yoshihisa Hirano. McNeil developed a reputation early in his Major League career as a "throwback" player notable for his high contact rate and low strikeout rate. On June 30, 2019, McNeil was selected as a reserve to the 2019 Major League Baseball All-Star Game NL team, his first selection. At the time of his selection, he led the majors with a.348 batting average. On August 5, 2019, McNeil recorded his 200th career hit in his 599th career at bat, becoming the fastest player in Mets history to 200 career hits. In 2019 he batted.318/.384/.531 with 23 home runs and 75 RBIs. He swung at the highest percentage of pitches, and the highest percentage of pitches inside the strike zone, of all major league batters.
Personal life
McNeil married his wife Tatiana on February 3, 2018 in Nipomo, California. The couple adopted a dog during the 2019 season which became "a social media sensation."