Walter was promoted to Triple-A Worcester on Monday, Chris Cotillo of MassLive.com reports.
Walter, a left-hander selected in the 26th round of the 2019 draft, has seen his stock rise rapidly since 2021. After the pandemic wiped out the 2020 minor-league season, Walter posted a 2.92 ERA over 25 games (14 starts) between to stops in the minors. He opened 2022 at Double-A Portland and has a 2.88 ERA with 68 strikeouts and just three walks over nine starts, spanning 50 innings. His fastball tops out at 95 mph, and he supplements that pitch with a changeup and slider.