The Red Sox have promoted pitching prospect Hayden Mullins from Double-A Portland to Triple-A Worcester, as was first reported by Tommy Cassell of The Worcester Telegram & Gazette.
Mullins was slated to start Worcester’s series opener against Rochester at Polar Park on Tuesday, but it was postponed due to inclement weather. The 25-year-old left-hander will now presumably get the starting nod and make his Triple-A debut in either Game 1 or 2 of Wednesday’s scheduled doubleheader.
Mullins is reaching the minors’ highest level for the first time following an up-and-down start to his season with Portland. In 12 outings (11 starts) for the Sea Dogs out of the gate, the southpaw posted a 5.85 ERA with 73 strikeouts to 31 walks over 47 2/3 innings in which Eastern League opponents batted .215 against him. That includes a .182 mark against left-handed hitters and a .236 mark against right-handed hitters.
Among 49 pitchers who entered play Tuesday having thrown at least 45 innings in the Eastern League this year, Mullins ranked first in strikeouts per nine (13.78), second in strikeout rate (34.8%), fourth in swinging-strike rate (15.7%), sixth in batting average against, 16th in FIP (4.16), and 17th in xFIP (4.13). On the flip side, he also ranked 28th in WHIP (1.43), 40th in ERA, and 46th in walks per nine (5.85) and walk rate (14.8%), according to FanGraphs.
Mullins is currently ranked by Baseball America as Boston’s No. 21 prospect, placing 12th among the system’s pitchers. The Tennessee native was originally selected by the Red Sox in the 12th round (369th overall) of the 2022 draft out of Auburn. He signed for just $97,500 but did not make his professional debut until the following August, as he was recovering from the Tommy John surgery that cut his junior season short.
After splitting the remainder of the 2023 campaign between the Florida Complex League and Low-A Salem, Mullins spent all of 2024 and the first part of 2025 with High-A Greenville before arriving at Portland last April. He fared well in his first stint with the Sea Dogs despite missing time in May due to shoulder fatigue, forging a 2.44 ERA across 18 starts (84 2/3 innings) en route to being recognized as the team’s Pitcher of the Year.
Even in light of that production, Mullins was somewhat surprisingly left off the Red Sox’ 40-man roster last November, leaving him available to other clubs in December’s Rule 5 Draft. He did not get picked, however, and remains in the organization without occupying a 40-man spot.
Listed at 6-foot and 194 pounds, Mullins possesses plus extension and features a 93-94 mph fastball that is capable of reaching 96 mph. The lefty also mixes in an 81-85 mph slider, a 77-80 mph sweeper, an 81-83 mph changeup, and a recently-implemented cutter. His secondaries are considered by Baseball America to be “inconsistent,” even though they “can all miss bats.”
Mullins, who turns 26 in September, can once again become Rule 5-eligible this winter if he is not added to Boston’s 40-man roster by the November protection deadline. Barring a trade or another move between now and then, he can further strengthen his case for a roster spot with a strong showing down the stretch at Worcester.
(Picture of Hayden Mullins: Kelly O’Connor/sittingstill.smugmug.com)
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