The Miami Marlins signed left-handed reliever John King to a one-year deal, adding a ground-ball specialist to stabilize a bullpen full of question marks.
The Miami Marlins didn’t just add another arm to their bullpen this week -- they added a very specific skill set.
ESPN's Jeff Passan first reported the Marlins' pick-up on Wednesday.
By agreeing to a one-year, $1.5 million deal with left-handed reliever John King, the Marlins are betting on something they clearly value: ground balls, weak contact and a veteran presence in a bullpen filled with question marks.
On the surface, King’s 2025 numbers with the St. Louis Cardinals don’t jump out. He posted a 4.66 ERA in 51 appearances and struck out just 12.6 percent of hitters, a career low. His sinker velocity dipped slightly, and he was non-tendered in November.
But context matters.
Over the last four seasons, King owns a 3.70 ERA across 243 innings. His calling card has never been swing-and-miss stuff. It’s extreme ground-ball contact. His career 61.5-percent ground-ball rate is elite, and in 2023, it ballooned to nearly 67 percent. Opponents simply struggle to elevate the baseball against him. That’s not flashy, but it’s valuable, especially in a league where hard contact in the air can change a game in one swing.
For Miami, this signing makes sense when you look at the current bullpen landscape under manager Clayton McCullough.
Andrew Nardi is coming off a lost season due to injury. Cade Gibson impressed as a rookie, but outperformed his underlying metrics. Josh Simpson has intriguing minor-league numbers, but struggled badly in limited big-league action. There was no clear, stable left-handed option with a track record.
King provides that.
He’s not a closer. He’s not a strikeout machine. But he is predictable in a good way. He limits home runs (0.89 HR/9 for his career), keeps the ball on the ground, and has historically handled left-handed hitters well (.251/.291/.337 career slash allowed). That matters in late-inning matchup spots.
There’s also a subtle roster angle here. King enters 2026 with just over four years of service time, meaning he remains arbitration-eligible through 2027. This isn’t a pure rental. If he rebounds to his 2021–2024 form, Miami controls him for another season.
For a front office that values flexibility and cost control, that’s not insignificant.
Yes, there are red flags. Right-handed hitters have hit him hard throughout his career. His strikeout rate, which has been trending downward, is concerning. But at $1.5 million, this is a calculated bet, not a franchise-altering gamble.
And it fits what the Marlins have quietly prioritized this winter: bullpen stability. After adding right-handers like Pete Fairbanks and Chris Paddack, this move balances the group with a veteran lefty who brings experience from both Texas and St. Louis.
Sometimes the smartest signings aren’t the loudest.
King may not headline a press conference, but if he keeps the ball on the ground in key moments at loanDepot park, this deal could look like one of Miami’s more practical -- and effective -- moves of the offseason.
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