The pitcher's penalty will take effect at the start of next season, the commissioner's office said. Hernandez most recently was with Triple-A Round Rock of the Pacific Coast League.
Hernandez made four starts for the Astros this season, going 0-3 with an 8.38 ERA. He also pitched for the Kansas City Royals from 2002-03 and 2005-06. The right-hander has a major league record of 25-36 with a 5.50 ERA in 82 career games, all starts.
A total of 54 minor leaguers have received bans since July 25, including 39 from the Dominican Summer League and 10 from the Venezuelan Summer League.