But Miami did lose the services of right-handed reliever Evan Reed, who was claimed by the Tigers.
The Marlins designated all four for assignment on Sunday to free up space on the 40-man roster.
Hernandez, a terrific defensive outfielder, will play center field at New Orleans. The native of Venezuela was acquired last July for Gaby Sanchez.
Maine is a left-handed reliever, and Cox will mix in at third base in Jacksonville.
Joe Frisaro is a reporter for MLB.com. He writes a blog, called The Fish Pond. Follow him on Twitter