The Orioles released Mattson on Monday.
Mattson reached the majors for the first time in 2021 and made four appearances out of the Baltimore bullpen, but he was outrighted off the 40-man roster in the spring and had pitched exclusively at Triple-A Norfolk this season. Over his 17.2 innings with Norfolk, Mattson turned in a 6.62 ERA, 1.81 WHIP and 14:20 K:BB.