Last season Fernandez made 28 starts, going 12-6 with a major league-best .182 opponents' batting average. His 2.19 ERA was second in the majors behind three-time defending ERA champ Clayton Kershaw.
Right-hander Anthony DeSclafani will be promoted from the minors and start Wednesday night in his major league debut.
"He's a guy that's done well in the minor leagues and we felt like he was probably the most ready to make the start," Redmond said.
"If we didn't have to use ( Kevin) Slowey and ( Brad) Hand so much on this road trip, maybe one of those guys would have gotten the start. But we've had to use them a lot, so we really needed a fresh arm. So that definitely played into it."
The 24-year-old former University of Florida star was 3-4 with a 4.19 ERA in eight starts at Double-A Jacksonville.
"Out of all of our younger guys, he's probably a little more polished because he's a college guy and he's got a few more innings under his belt, as far as experience," Redmond said. "There's no doubt that losing Jose is a big blow, but it's also an opportunity for guys to step up and show what they can do."
Information from The Associated Press was used in this report.