Scouting Report

Scouting grades: Fastball: 55 | Slider: 50 | Changeup: 50 | Control: 45 | Overall: 40

Mullins ranked among the best high school left-handers in the 2019 Draft but had elbow problems that spring that persisted through his three seasons at Auburn, where he worked just 53 1/3 innings before having Tommy John surgery in 2022. A 12th-round pick that July, he posted some of the best numbers (2.21 ERA, .177 opponent average, 30 percent strikeout rate) in the Red Sox system last year despite missing three weeks with shoulder fatigue in May. Boston gambled by not adding him to its 40-man roster in November and was glad that he slipped through the Rule 5 Draft without getting taken.

Mullins has one of the better bat-missing fastballs among Red Sox farmhands, thanks to tremendous carry that helps it play significantly better than its 91-95 mph velocity. While his low-80s slider can feature big sweep and grade as a plus pitch at its best, it was more of an average offering last year. His sinking low-80s changeup is similarly effective, and he also has begun working on a cutter with similar velocity.

There's a lot going on in Mullins' delivery, which features a big leg kick, a twist that hides the ball behind him and a low release point. All of that provides deception but hampers his ability to find the zone, and he never has demonstrated better than fringy control or command. He could be a No. 4 starter if his secondary pitches and strikes improve, and he may be of more immediate big league help as a multi-inning lefty out of the bullpen.

Scouting grades: Fastball: 55 | Slider: 55 | Cutter: 55 | Changeup: 50 | Control: 45 | Overall: 45

One of the top prep southpaws in the 2019 Draft, Mullins battled elbow problems that spring and throughout his time at Auburn, totaling just 53 1/3 innings in three college seasons before having Tommy John surgery in 2022. After the Red Sox drafted him in the 12th round that July, he didn't make his pro debut until the end of the 2023 season. He posted a 3.94 ERA with 118 strikeouts in 89 High-A innings last year and earned a swift promotion to Double-A in 2025.

Mullins' fastball operates in the low 90s and tops out at 95 mph, yet it misses plenty of bats because it features tremendous carry up in the strike zone. He'll flash a plus low-80s slider with two-plane depth at times and can turn it into a harder, tighter cutter that's similarly effective. His low-80s changeup lacks the consistency of his other offerings but has quality tumble at its best and helps him keep right-handers in check.

Mullins' delivery comes with a big leg kick, a twist that hides the ball behind him and a low release point, all of which help him create deception. He exhibited fringy control in college and during his first full pro season, so he'll need to improve his strike-throwing to become a No. 4 or 5 starter. If not, he could have a future as a multi-inning lefty reliever.

Scouting grades: Fastball: 55 | Slider: 55 | Changeup: 50 | Control: 45 | Overall: 40

One of the top high school left-handers in the 2019 Draft, Mullins battled elbow problems that spring and through his career at Auburn, working just 53 1/3 innings in three college seasons before having Tommy John surgery in 2022. The Red Sox still selected him in the 12th round that July and he didn't make his pro debut until the end of the 2023 season. Fully healthy in 2024, he posted a 3.94 ERA with 118 strikeouts in 89 High-A innings.

While Mullins' fastball doesn't have notable velocity, sitting in the low 90s and peaking at 95 mph, it misses plenty of bats because it has tremendous carry up in the strike zone. He'll flash a plus low-80s slider with two-plane depth at times, and also will turn it into a harder, tighter cutter. His low-80s changeup isn't as reliable but has quality tumble at its best and helps him keep right-handers in check.

Mullins creates deception with his delivery, which features a big leg kick, a twist that hides the ball behind him and a low release point. He exhibited fringy control in his first full pro season and will need to improve his strike-throwing to become a No. 4 or 5 starter. If not, he could have a future as a lefty reliever with two solid offerings.

Transactions

Team	Date	Transaction
	03/05/2026	LHP Hayden Mullins assigned to Boston Red Sox Prospects.
	05/25/2025	Portland Sea Dogs activated LHP Hayden Mullins from the 7-day injured list.
	05/05/2025	Portland Sea Dogs placed LHP Hayden Mullins on the 7-day injured list.
	04/29/2025	LHP Hayden Mullins assigned to Portland Sea Dogs from Greenville Drive.
	04/02/2024	LHP Hayden Mullins assigned to Greenville Drive from Salem Red Sox.
	04/02/2024	Greenville Drive activated LHP Hayden Mullins.
	08/27/2023	Salem Red Sox activated LHP Hayden Mullins from the 60-day injured list.
	08/17/2023	Salem Red Sox sent LHP Hayden Mullins on a rehab assignment to FCL Red Sox.
	08/17/2023	Salem Red Sox sent LHP Hayden Mullins on a rehab assignment to FCL Red Sox.
	04/05/2023	LHP Hayden Mullins and assigned to Salem Red Sox from FCL Red Sox.
	11/08/2022	FCL Red Sox activated LHP Hayden Mullins.
	08/18/2022	LHP Hayden Mullins roster status changed by FCL Red Sox.
	08/15/2022	LHP Hayden Mullins assigned to FCL Red Sox.
	07/29/2022	Boston Red Sox signed LHP Hayden Mullins.
	02/04/2022	LHP Hayden Mullins and assigned to Auburn Tigers.
	08/09/2018	LHP Hayden Mullins assigned to PG East.