Isaac Mattson Looking for Ways to Improve Even After Breakout Season With Pirates
Life looks a lot different for Isaac Mattson than it did this time a year ago.
Mattson is the father of soon-to-be one-year-old, Teddy, who was born during spring training at the end of last February.
Professionally, Mattson’s career blossomed during his second season with the Pittsburgh Pirates.
The Pirates signed Mattson as a minor-league free agent in the 2023-24 offseason and the right-hander made three appearances out of Pittsburgh’s bullpen at the end of the ’24 season — his first big-league action since making four appearances with the Baltimore Orioles in 2021.
Mattson re-upped with the Pirates on another minor-league deal last offseason, and while a second chapter with the organization started the same, it looked much different when the book was closed on 2025.
The 30-year-old Mattson emerged as a key piece in the Pirates’ bullpen after he was recalled in May and finished the season with 44 appearances — the third-most of anyone to take the mound for Pittsburgh last season.
Even though he showed sustained success, Mattson used the year to continue to learn and get better.
“Every experience I had last year, whether it was good or bad, it was something to learn from,” Mattson explained. “But definitely that confidence piece was huge knowing what 2024 taught me and going into 2025 and being able to grow from that. And now, just being able to know I can do that consistently.”
Mattson ended the season 3-3 with a 2.45 ERA and held opponents to a .203 batting average and a .600 OPS. One of his highlights came on June 7 against the Philadelphia Phillies at PNC Park on June 7 when he earned his first-career win.
So why have things worked so well in Pittsburgh?
“I think the biggest piece was just the belief piece from the Pirates knowing they had my back in ’24 and signing me back in ’25 and just being able to go out and know who I was and execute at a high level,” said Mattson.
In addition to the confidence boost Mattson received by the trust the Pirates showed in him, Mattson’s effectiveness is at least in part due to one of the weapons in his arsenal.
Mattson’s “disappearing” fastball proved to be a weapon that often left opposing hitters scratching their heads. The pitch averaged just 93.9 mph on the radar gun but is deceptive thanks to the extension he gets on the mound. Last year, opponents hit just .191 against it.
“Yeah, I don’t think it’s a secret anymore. I think the cat’s out of the bag,” said Mattson. “It’s a pitch that I’ve thrown pretty much my whole life. Being able to hear that [PitchCom] button being pushed and knowing that the organization believed in that is huge.”
With that pitch still the key piece of his repertoire, Mattson has been focused this offseason on trying to round out the rest of his offerings with an emphasis on improving his changeup.
“I felt like, especially the second half of the season, learned some lessons to grow from,” Mattson explained. “Worked on the changeup a lot this year. Gonna work on that continuing through spring training and just try to refine that to where it needs to be. I’m excited for where that can take me.”
Most relief pitchers have at least two offerings that they alternate between to keep hitters off balance. But for Mattson, he relied primarily on challenging hitters with his fastball, which he threw 78% of the time. His changeup made up 12% of his offerings and he threw a slider 9% of the time.
While Mattson will surely still favor his fastball this coming season, expect to see at least a few more secondary pitches.
“Taking that next step this year, being able to execute other pitches in the zone. Not that I didn’t have confidence in them last year, but now the usage can be a little bit more dynamic and not being the same guy every day,” Mattson said. “Being able to throw pitches in the zone with confidence is kind of the big next step.”
Mattson will arrive at Bradenton for spring training in a much different position than he did last year. This time, he’ll be viewed as a key piece of the bullpen plans, and he has high hopes for what the unit is capable of.
“It’ll be really fun to see just how filthy we can be this year,” he said.
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Love this guy. So easy to root for. High School, college, and pros, all in Western Pennsylvania. An absolute bulldog on the mound.
He just scares me to death with that 94 mph fastball that he just keeps pounding at the top of the zone. They just can’t barrel it, but I wouldn’t count on that continuing. That’s why I am glad to hear that he is adapting and exploring other pitches, especially for lefties. I would love to see a splitter or something.
He’s an easy guy to root for.
What I like about him is he challenged hitters held nothing back, but changed up at the right moment. Hope to see a lot of him this year.