MIAMI, FL—Several minor league free agent signings have seen some action for the 2025 Miami Marlins, including Ronny Simon, Heriberto Hernández and Rob Brantly, but right-hander Janson Junk has separated himself from the rest. Assumed to be another depth arm that would come up and down from Triple-A Jacksonville, Junk is having far too much success to consider sending down. It’s now a question of what his role will be in Miami for the rest of the season and potentially future years.
Junk bounced around quite a bit prior to signing with Miami. Originally drafted by the New York Yankees, he was traded twice and claimed off waivers twice. He had already pitched in the majors with three teams, but the results weren’t promising (6.75 ERA and 5.07 FIP in 40.0 IP).
However, Junk opened eyes in spring training and was one of the final non-roster invitees in contention for an Opening Day roster spot. He was assigned to AAA instead, but made the most of it. During nine appearances (eight starts) with Jacksonville, the 29-year-old posted a 2.78 ERA, 2.57 FIP, 7.94 K/9 and 1.39 BB/9 through 45 ⅓ innings pitched.
Junk tells Fish On First what was different about the most recent call-up he received two weeks ago:
“That was the first time getting called up in person…To have the experience of getting back and sharing that moment with (Jacksonville manager) David Carpenter and the excitement from the guys in the locker room, that was really special. It was cool seeing on the schedule that we were going to Anaheim, back to the spot where I made my debut. Haven’t been back there. When I was with the Brewers, I was never able to go there. It was a full-circle moment.”
Facing the Los Angeles Angels on May 24, Junk went five innings, allowing one run on six hits, one walk and struck out four. He became the first pitcher in Marlins history to pitch five-plus relief innings and finish a game in which Miami won. He was also credited for the save.
All three appearances for Junk this season have come in long relief, posting a 1.38 ERA, 1.00 FIP, 10.4 K/9 and 0.7 BB/9 in 13 innings pitched. Coincidentally, all of his outings have been piggybacking starter Cal Quantrill and they have split the workload very evenly (13.1 IP for Quantrill in those three starts).
In addition to his mid-90s fastball and slider, Junk’s pitch mix consists of a sweeper that he uses to put away righties and occasional curveballs and changeups against lefties.
Junk has walked only one batter with the Marlins. Since spring training, he says he has been sticking to his plan of “filling up the zone, understanding that my pitches get outs.”
According to Baseball Savant, Junk is locating 60.7% of his pitches in the strike zone. That is not only the highest rate on the Marlins, but second-highest amongst all MLB pitchers who have thrown at least 100 pitches this season. He is constantly ahead in the count with an elite first-pitch strike rate of 77.6%.
Moving forward, Junk may have to be more careful. It hasn’t come back to bite him yet, but his opponents have a massive 60.6% hard-hit rate. He has been barreled up four times, even though none of them have produced home runs. Keeping the ball in the park was a big problem with his previous teams.
After getting stretched out as a starter this season, he’s had to adjust to this new role.
“Luckily, I had experience last year coming out of the ‘pen with the Brewers, so I kind of built some type of routine out of the bullpen,” said Junk. “I can take things from what I learned through that process…I get my treatment, recovery, lifts, but once I’m fresh, it’s all bullpen. I’m totally thinking about the bullpen, warming up every few innings, getting locked in. So far, it’s been a good transition.”
Expect Junk to continue as a long reliever until the Marlins suffer another starting rotation injury or trade one of their veteran arms such as Quantrill, who is a pending free agent. During the second half of the season in all likelihood, there will be an opportunity for him to start games consistently.