How 'more unpredictable' pitch usage has fueled John King's early success with Marlins

MIAMI, FL — The Miami Marlins took a different approach to free agency last offseason compared to previous years of the Peter Bendix era. They signed four different veterans to major league deals (five if you also include Austin Slater at the end of spring training). Without question, left-hander John King has been the best of them all thus far, not to mention the top reliever on the entire team.

Through his team-leading 15 appearances entering Saturday, King has a 0.66 ERA, 3.72 FIP, 8.56 K/9 and 3.29 BB/9. His ERA is tied for 10th-lowest among qualified MLB relievers. He has allowed only two hits. That is $1.5M very well spent.

"He's shown he's been incredibly durable, and someone who always wants the ball no matter what," Marlins manager Clayton McCullough said on Friday. "The situation is not always the greatest, but what John does and his ability to come in and collect outs helps us win games. It also helps keep guys fresh."

So far this season, the Marlins have used King in all kinds of situations. He has been especially effective in what Baseball-Reference defines as high-leverage moments, retiring all seven batters faced.

"I feel like as pitchers, you face those guys are kind of like are bigger than baseball itself," King said. "I just think that treating them like everyone else and just attacking, getting ahead—their numbers go down when you get ahead of one versus one. Obviously, they capitalize on mistakes. Even probably more so, they hit great pitches. I think putting yourself in the best opportunity for success is getting ahead. I just think that with experience, the game kind of has slowed down for me."

In the past series against the Los Angeles Dodgers, King was utilized in all three games. He tossed 2 ⅔ total shutout innings in a Marlins series win.

"I think going into it, it's something John had done in the past," McCullough said of using him three consecutive days. "Him coming into spring training, he can handle it. Generally, his workload, the amount of hitters asked him to face, is a little bit narrower than some other guys."

Previously a member of the St. Louis Cardinals, King's 2025 season was one of the worst of his career, where in 48 ⅓ innings pitched, he posted a 4.66 ERA, 5.00 FIP, 5.21 K/9 and 2.61 BB/9. King's agent is friends with Bendix and was encouraged by what the Marlins organization had been doing with player development on the pitching side, leading to an agreement.

"The hot run that the team went on last year and just being in Miami is sweet, too," King told Fish On First. "There's a lot of things that I was really excited talking to them about and seeing if we could work something out. I was fortunate enough they offered me a deal, and I took it right away."

Unusual for a reliever, King has a six-pitch arsenal. He also did last season, but relied heavily on his sinker, using it 59.2% of the time. With the Marlins, that usage has been cut in half to 28.7%. Although his sinker's velocity has dropped, its whiff rate has gone way up from 15.7% to 40.9%.

"I had become super predictable throwing it that much," King said. "In spring training, I had a meeting with some of the front office and pitching staff, and they told me how they want me to mix and they want me to throw a sweeper. I can command the ball pretty well, and I'm still learning to command the breaking stuff as well as the sinker and changeup. I think putting it all together just makes me a little bit more unpredictable and a little bit more uncomfortable with that, especially with righties."

King was terrible against right-handed batters last season, allowing a .374/.437/.542/.979 slash line. On the other hand, he's dominating them with the Fish (.050/.208/.200/.408 in 24 PA).

King has yet to enter in any save situations, but that may change in the coming weeks. With Pete Fairbanks sidelined due to nerve irritation, the Marlins are using a closer-by-committee approach. If favorable matchups present themselves in the ninth inning, King should be trusted to get the job done.