Greg Allen was born and raised in San Diego. He attended Hilltop High School in Chula Vista before playing his college ball at nearby San Diego State University. After three years with the Aztecs, Allen played with the Orleans Firebirds of the Cape Cod Baseball League during the summer of 2013.
The 6’0, 185-pound Allen was taken in the sixth round of the 2014 draft by the Cleveland Indians with the 188th pick. He made his major league appearance for the Indians on September 1 of the 2017 season.
Allen was acquired by the Padres on August 31 of this year in the trade for ace Mike Clevinger.