19-year-old Elvis Luciano becomes the first player born in the 21st century to appear in a major league game when he makes his debut for the Blue Jays against the Tigers. Never having pitched above Rookie-class before this season, he allows just 1 hit in 1 1/3 inning in a successful outing. This coincides with the last two players who were active in the previous century, Adrian Beltre and Bartolo Colon, both being out of the majors as a page has clearly turned.

On March 31, 2019 — 19-year-old Elvis Luciano becomes the first player born in the 21st century to appear in a major league game when he makes his debut for the Blue Jays against the Tigers. Never having pitched above Rookie-class before this season, he allows just 1 hit in 1 1/3 inning in a successful outing. This coincides with the last two players who were active in the previous century, Adrian Beltre and Bartolo Colon, both being out of the majors as a page has clearly turned.

Sources –
Baseball Reference March 31
SABR Games Project
National Pastime March 31
Retro Sheet
Replay The Game