Know Your Orioles 40-man: Isaac Mattson

This article is part of the Know Your Orioles 40-man series, which features an article about each of the 38 players currently on the Orioles roster. There will be one every weekday until we run out of players.

Note: On 4/8/22, the Orioles announced Isaac Mattson had cleared waivers and was outrighted to Triple-A Norfolk. He is no longer on the Orioles 40-man roster.

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. For what it’s worth, after Mattson returned from the IL in September, he rattled off three scoreless appearances with eight strikeouts for the Tides.

The Orioles may not have seen the best version of Mattson, one of four pitchers acquired from the Angels in the Dylan Bundy trade in December 2019. While not a hyped prospect, Mattson put up solid numbers for three seasons in the Angels’ system after being drafted from the University of Pittsburgh in the 19th round in 2017. He had reached Triple-A Salt Lake and was coming off a strong performance in the Arizona Fall League at the time of the trade. Like every other minor leaguer, though, his 2020 season went up in smoke thanks to the pandemic.

Despite a shaky first season of action in the Orioles’ organization, Mattson has shown the potential of being a useful bullpen piece, racking up a career 11.1 strikeout rate in the minors, including 12.5 for Norfolk last season. Unlike most relievers, who are failed starters, Mattson has worked almost exclusively from the bullpen ever since his college days; all but one of his 60 appearances in three years at Pitt came in relief. He even had a previous stint in Charm City in the summer of 2015, posting a flawless 0.00 ERA in 11 relief appearances for the Baltimore Redbirds of the Cal Ripken Collegiate Baseball League.

Mattson’s not a guy who’s going to blow hitters away with velocity, averaging just under 93 mph on his fastball in 2021, but he also flashed a slider, curve, and changeup as part of a four-pitch mix. FanGraphs’ Eric Longenhagen, in ranking Mattson the Orioles’ #25 prospect before the 2021 season, wrote that Mattson’s backspinning heater “plus his slider, will be enough for a middle-inning role.”

There’s a reason Mattson finds himself still holding onto a roster spot while other 2021 Norfolk-shuttle relievers — Conner Greene, Dusten Knight, and the like — didn’t. He has the kind of upside those guys didn’t, and at 26, he’s still young enough to develop into a useful big league reliever, even if he’ll never be a closer type.

End-of-year prediction: The 2022 season may start out the same as 2021 for Mattson — shuttling back and forth between Baltimore and Norfolk for a while — but he should get plenty of chances to earn a longer stint in the Orioles’ bullpen during the year. It’s not as if there are a ton of established veterans among the Birds’ relief corps. He finished 2021 in the big league bullpen as an extra arm; I predict he’ll also finish 2022 in the majors, this time with a sturdier hold on a middle-relief role.

Previously: Félix Bautista, Logan Gillaspie

Tomorrow: Cionel Pérez