Wolf, who has overcome two Tommy John surgeries, had been pitching for Triple-A Reno, in the D-backs' system.
"He's a stabilizer," Michael Hill, the Marlins' president of baseball operations, said. "He's a proven Major League veteran starting pitcher. We know we have a young staff. To have a veteran in that group is not a bad thing. What we've gone through the past few days, that did play into it, bringing in a veteran. A strike-thrower."
Miami moved aggressively in its search for a big league pitcher with starting experience after the severity of Fernandez's injury was revealed. The 21-year-old ace has sustained a substantial ligament tear to his right elbow, an injury that will require Tommy John surgery.
"It came together very fast," said Wolf, who exercised his out clause with the D-backs and signed with the Marlins for $1 million. "It kind of feels like a first-time callup. I was excited about the opportunity."
Of course, if Fernandez hadn't been injured, this match likely wouldn't have happened.
Wolf was aware of Fernandez's situation and understands the impact it has on the Marlins as an organization.
"I was aware of it pretty early," Wolf said. "Watching him from afar, you can tell he is an emotional kid. That's what makes him so dynamic as a pitcher, a player and a presence on a team.
"It was not only a physical blow to a team, it was an emotional blow for ... an organization to lose a guy like that, who is probably the most exciting young guy since Dwight Gooden. I think that's the best comparison. That's always a blow to a team. It's definitely unfortunate for a team, but at the same time, he's 21 years old, but I've been there. I've done it a couple of times."
After Tuesday's loss, the team designated reliever Henry Rodriguez for assignment and optioned lefty Dan Jennings to Triple-A New Orleans.
Miami on Wednesday selected the contract of 24-year-old right-hander Anthony DeSclafani, the club's No. 6-ranked prospect, from Double-A Jacksonville. He made his Major League debut with a start against the Dodgers.
Following DeSclafani's start, the Marlins will reassess the rotation. In time, Wolf could slide in.
"Just like our regular lineup, surrounding our veterans with good guys, winners, basically, that's what we've done here with the pitching staff," manager Mike Redmond said. "He's been around. He's seen a lot of stuff and been a great teammate."
Wolf is 132-117 with a 4.20 ERA in his 14-year big league career. He last pitched in the Majors in 2012, with the Orioles.
He clearly isn't being asked to replace Fernandez, one of the game's dominating young pitching stars, but the hope is that he can add innings and keep his team in games.
At Reno, he had a 4.50 ERA in six starts.
"We're going to go through our ups and downs with our young staff," Redmond said. "We understand that going into it. It was a little bit different when Jose is at the head of it, because you can weather a lot when you've got that kind of stuff. Now we take a step back. We reassess where we're at."