June 18, 2017: The Angels RHP Isaac Mattson in the 17th round, out of the Univ. of Pittsburgh. He signed with scout Jared Barnes.

June 2025:  It may be quicker to list all the teams in Western Pennsylvania that Isaac Mattson has not picked up a win for.

An Erie, Pa., native, Mattson first made a name for himself at the University of Pittsburgh. After a brief stint with the Orioles in 2021, he started his road back to the Majors in 2022 with the nearby Washington Wild Things of the independent Frontier League. When he joined the Pirates last season, he picked up a couple of wins for the Double-A Altoona Curve.

On June 7, he finally got the big one, his first Major League win, and at the crown jewel of the area’s ballparks, PNC Park. The 29-year-old right-hander stranded an inherited runner on third in the seventh inning, setting up Henry Davis for a go-ahead home run in the home half of the frame as the Pirates came back to beat the Phillies, 2-1. 

“It's a really cool accomplishment knowing how many games we came to as a family,” Mattson said. “Being able to be on the other side of it and help the team win, it's pretty cool." Starter Andrew Heaney was rolling through six innings, but was removed after he started to experience left calf muscle cramping in the seventh. Mattson entered with a runner on third, no outs and a 2-0 count, but got Nick Castellanos to strike out, J.T. Realmuto to pop out to shallow right and pinch-hitter Bryson Stott to fly out to escape the jam.

"Henry did a great job of guiding me through the inning,” Mattson said. “When I got here today, he was just like, 'Strength of attack,' so that was the focus going into the outing. When they pinch-hit the third guy I ended up facing, having to face the lefty, he came out and did a great job of just running me through the attack plan. Credit to him for keeping me in the moment and just being able to focus pitch by pitch."

That inning wasn’t the only thing Mattson had to navigate. He also had to get to Pittsburgh. Endy Rodríguez was placed on the 10-day injured list with right elbow inflammation, so the Pirates selected the contract of catcher Brett Sullivan pregame. They needed to open a spot, so reliever Joey Wentz was designated for assignment, and Mattson was called back up after an earlier cameo with the team last month. 

Mattson woke up in Memphis, Tenn., with Triple-A Indianapolis, but arrived at the ballpark around 1:30 p.m., well into his normal workday. He has been here before and knew the routine, which helped guide him through the day. It turns out having that experience at the big Western Pennsylvania ballparks is advantageous.

“I get chills thinking about that,” manager Don Kelly said. “That's storybook right there. For him to have that moment -- talk about the crowd, the energy today was fantastic.”

Even without the local angle, Mattson is an easy person to root for. In May, he donated $50 per strikeout to Mental Health of America, a cause that hit home after his mother took her life after a battle with depression in 2021. He’s worked to try to help awareness in recent years, and it’s part of his journey back to the Majors after a three-year gap before being recalled last September.

“Phenomenal person, phenomenal story,” Davis said. “Indy ball to the big leagues, coming in in a moment like that and just trusting your stuff and getting us through a big moment was huge.” Talking with reporters postgame, Heaney downplayed the severity of his calf injury. How often do you hear a starting pitcher get removed mid-quality start, see someone else get the win and call it “a fun win?”

That’s pretty indicative of the impact Mattson’s performance had.

"If you're going to get one, get one like that,” Heaney said. “That's an amazing way to get it. He was here before, he came in and pitched well, pitched with emotion. And so I think he's the right guy in that moment to come in and get three big outs for us right there. Just happy for him. He deserves it. He's worked hard for it." (A Stumpf - MLB.com - June 7, 2025)

Aug 16, 2025: Written on the side of Isaac Mattson's glove in mint-blue lettering is the name “Theodore Oakley.” It’s a name that he quite literally holds close to his heart as he sets up for every pitch, and someone he credits his success to in his breakout season. Coming into the year, Mattson had pitched just seven Major League games. Now, he’s emerged as one of the Pirates’ top leverage arms.

When pitching coach Oscar Marin and manager Don Kelly reflect on when they thought Mattson could emerge as a legitimate bullpen arm, they both go to his appearance this Spring Training against the Yankees in Tampa. Mattson had been sitting around 91 mph in camp to that point, but in that March 16 game, he was hitting 94-95 mph. He’s held that velocity this season, and with his arm angle, Marin describes his fastball as “invisible” at that speed.

That game in Tampa was Mattson’s first game back after meeting Theodore, or “Teddy.” He and his wife, Devin, welcomed him into the world on Feb. 26, and their first child also brought the changes Mattson needed to become the best version of himself on the mound.

“Definitely some dad strength, definitely some perspective shift,” Mattson said, a parent himself now after using his platform with the Pirates the last two years to tell the story of his mom.

Mattson’s baseball journey has been one of resilience. After debuting with the Orioles in 2021, he found himself out of affiliated ball and pitching for the local Washington Wild Things of the Frontier League in 2022. When he signed a Minor League deal with the Twins in 2023, his first game back in Double-A was defined by him walking the bases loaded and allowing a game-losing grand slam.

Games like that had him wondering what he was doing. He was better than a lot of these players, or at the very least, he should be better. He and Devin talked and prayed, wondering if the Major League dream was still worth pursuing. Mattson, an Erie native and Pitt graduate, signed a Minor League deal with the Pirates in 2024 and excelled. The highlight of the campaign was a trip to Rochester, N.Y. for a Kenny Chesney concert, where Devin gave Isaac a friendship bracelet that said “Dada.”

Becoming a father was a catalyst for Mattson. He can’t just have those games where he left thinking he should have been better. He needed to be better.

“Down in Florida, just sitting at my Airbnb after practice each day, just giving my wife and Teddy calls throughout the afternoon and work day, the perspective shifted,” Mattson said. “This is what I’m deciding to do, taking away that time from people that I want to be around and spend this time with.

“If I’m not able to do that, then I really want to give it all I got. Do it for them. Do it for what’s important, which is family.”

Mattson has seven siblings and now 20 nieces and nephews. Growing up, he and his family would do child care for Sunday School every other week. Fatherhood always seemed like a calling, following the example his parents, Edward and Debra, set.

Parenthood has been a theme of Mattson’s career even before Teddy. His mother, Debra, took her life in July of 2021, and he has used his platform to raise awareness on mental health. The Mattson family also organized a walk to raise money for scholarships in her name.

Mattson learned a lot about being a parent from Debra, especially on unconditional love. He remembers the support that she gave each kid, taking them to practices or events and showing that she cared and would be there. “I’m trying to take that into my own experience as a parent now,” Mattson said. “Try to encourage, even though he doesn’t know what’s going on. Just try to be that positive person. I’m trying to honor her as a parent myself.”

Mattson is trying to be that supportive, loving figure in his son’s life now, even if he’s just now only starting to recognize his name. He doesn’t know what baseball is yet or what dad does, but he’ll be in attendance.

“It’s always nice to have him in the stands, even if he won’t remember,” Mattson said. “My wife and I will.” (A Stumpf - MLB.com - Aug 16, 2025)

TRANSACTIONS

June 18, 2017: The Angels signed RHP Isaac Mattson after picking him in the 17th round, out of the Univ. of Pittsburgh. He signed with scout Jared Barnes.

Dec 4, 2019: The Orioles traded RHP Dylan Bundy to the Angels; acquiring RHP Isaac Mattson, RHP Kyle Bradish, RHP Kyle Brnovich, and RHP Zach Peek.

Mattson has a 90-95 mph FASTBALL. His best pitch is a 55 grade CURVEBALL. He has a CHANGEUP.

Pure-stuff wise, Mattson is average across the board, with a three-pitch mix that he uses well. He’ll throw his fastball with good life. He mixes in an effective slider and a sinking changeup as well, using all quadrants of the strike zone effectively. Thanks to some deception in his delivery and his ability to command three offerings, he’s shown an ability to miss a lot of bats in the strike zone, as evidenced by his career 10.9 K/9 rate in the Minors.

Mattson tends to be around the strike zone more often than not, but because he doesn’t have plus stuff or a true out pitch, his ceiling in a big league bullpen might be limited to being a middle man or perhaps a setup man.

The Orioles liked his ability to get outs enough to add him to their 60-man player pool before the start of the 2020 season, though he wasn’t yet on the 40-man roster. (Spring 2020)

2021 Season: Whatever may lie ahead for Isaac Mattson’s big league career, he can always say his MLB debut was, well, unique.

The date was May 7, 2021, on a chilly evening in Baltimore, when the then-25-year-old Mattson completed his warmup tosses in the Orioles’ center field bullpen at Camden Yards. As the game entered the top of the ninth inning with the O’s trailing the Red Sox, the bullpen doors swung open. Mattson gloriously burst through, as his friends and family hooted and hollered from seats behind home plate, and the right-hander jogged his first few steps onto a major league field ...

... and then froze in his tracks. Dillon Tate, who’d finished the previous inning, had stepped out from the O’s dugout to take the mound. Mattson looked around, confused, only to realize that Brandon Hyde hadn’t summoned him into the game yet. Mattson awkwardly turned around and slinked back to the bullpen. Oops.

Nevertheless, Mattson’s debut was delayed by only one batter. Tate retired the leadoff man and then, as Hyde trotted to the mound to take the ball, it was Mattson’s turn. For real, this time. Nerves — and a patient Red Sox lineup — made it a somewhat shaky debut, as Mattson walked the first batter in a six-pitch at-bat and allowed an RBI double on the seventh pitch to Marwin Gonzalez before a couple of deep flyouts ended the inning.

That was the first of just four major league appearances for Mattson in 2021, each of which came in a different month of the season and each at least 25 days after the previous one. He was a frequent passenger on the Norfolk shuttle, making four trips up from and down to the Orioles’ Triple-A affiliate.

The fact that Mattson didn’t earn a longer stay at any point was somewhat disappointing, but his Triple-A performance simply didn’t warrant it. In 18 games at Norfolk, Mattson struggled to a 6.23 ERA and surrendered 24 hits in 17.1 innings. His big league ERA was an identical 6.23, albeit in an extremely small, 4.1-inning sample size. He also suffered a shoulder injury in August that landed him on Norfolk’s injured list for a month.  (Paul Folkemer - Feb 2, 2022)

Mattson made three relief appearances for the Pirates at the end of 2024, his first major league action since debuting with the Orioles in 2021. He then earned an extended big league opportunity last season, appearing in 44 games with a 3-3 record and a 2.45 ERA.

Why has Mattson found success with Pittsburgh but not in the minor leagues with the Los Angeles Angels, Orioles, or Minnesota Twins?

“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,” Mattson said. “I’ve had people surrounding me in my life, my wife being a huge piece of that, but my family as well, always believing in me and believing that we can do great things.

“Just to have the support of the Pirates and the guidance as well. It just adds on to that and gives you the confidence to go play free and enjoy the game just a little bit more.”

Currently, the Pirates' bullpen features Mattson and left-hander Gregory Soto as the likely primary setup men for closer Dennis Santana. This marks quite a jump for Mattson; less than three years ago, he was pitching in independent ball with Southern Maryland of the Atlantic League.

Despite his recent advancements, Mattson is more interested in looking ahead at this point.

“It means a lot knowing that this isn’t my story, knowing that God has had a hand in it the whole time,” Mattson said. “There will also be a time and a place to look back and reflect on all of that stuff. I don’t think I’m there yet, but maybe in a few years down the road, we’ll get there. Just thankful for where this game has taught me lessons about baseball, but also about life.”  (John Perrotto - Jan. 28, 2026 - PiratesRoundtable)