MLB Pipeline’s Jonathan Mayo listed 25-year-old Red Sox left-handed pitching prospect Hayden Mullins as one of 12 candidates to be taken in Wednesday’s Rule 5 Draft.

He’s the only Red Sox prospect who Mayo listed but there are others to watch as well.

A team that drafts a player in the Rule 5 Draft must give the player’s former club $100,000. The player then must remain on his new team’s active 26-man roster the entire regular season unless he’s injured or else be returned to his former team for $50,000.

Below are five prospects who the Red Sox could lose Wednesday:

Hayden Mullins, LHP

Mayo wrote, “A year ago, the White Sox nabbed Shane Smith with the No. 1 pick in the Rule 5, and he spent the year in their rotation. Mullins might be the best candidate to get the chance to start among those eligible. A 13.8 percent walk rate at Double-A might deter some, but he also struck out 30 percent of his batters faced for the year, getting swing-and-miss on his 91-94 mph fastball and low-80s two-plane slider.”

The Red Sox drafted Mullins in the 12th round out of Auburn University in 2022 after he tore the ulnar collateral ligament in his elbow during his final season with the Tigers. Tommy John surgery delayed his professional debut until August 2023.

He posted a 3.94 ERA while holding opponents to a .223 batting average in 22 outings (17 starts) for High-A Greenville in ‘24, his first full year back from injury. He finished with the fourth highest strikeout percentage (30.3%) among Red Sox minor league pitchers who faced at least 300 batters in 2024, punching out 118 of the 389 hitters he faced.

His ability to induce whiffs continued in 2025 when he again struck out 30% of the batters he faced. He went 8-2 with a 2.21 ERA and 1.11 WHIP while holding opponents to a .177 batting average in 22 outings (21 starts) between High-A Greenville and Double-A Portland in 2025. He recorded a 2.44 ERA and held opponents to a .175 batting average in his 18 starts for Portland.

Yordanny Monegro, RHP

The Red Sox faced a very similar situation last year with pitching prospect Angel Bastardo whose 2024 was cut short due to Tommy John surgery.

Boston left the talented right-hander unprotected in the Rule 5 Draft last December. At the time, Bastardo was 22, had never pitched above Double A and Baseball America ranked him Boston’s No. 27 prospect.

The Blue Jays selected him and placed him on the 60-day IL for the entire 2025 season. He now must remain on Toronto’s active roster for the full season in 2026 (barring an IL stint) or be returned to the Red Sox.

Monegro just turned 23 on Oct. 14, is coming off Tommy John surgery in June and MLB Pipeline ranks him Boston’s No. 26 prospect. So he’s in a very similar spot age-wise, prospect status-wise and health-wise as Bastardo last year. He also pitched for Double-A Portland pre-injury in 2025 like Bastardo did in 2024 before his injury.

It’s possible a team will select him, put him on its 60-day IL for the 2026 season and then let the Rule 5 roster rules apply in 2027.

Monegro, who stands at 6-foot-4, has a 3.22 ERA, .221 batting average and a 29.9% strikeout percentage in 63 minor league outings (57 starts). He had a 2.67 ERA in nine outings (eight starts) in 2025 before getting injured.

Jedixson Paez, RHP

It seems unlikely Paez would be selected in the Rule 5 Draft because the 21-year-old has not yet pitched above High-A Greenville.

He also missed much of ‘25 due to a calf injury.

But he does have excellent control with just 49 walks in 307 ⅔ innings in the minors and a 3.9% walk percentage. He also pitched well in his limited sample size last year, with a 2.79 ERA while holding opponents to a .228 batting average in seven starts for Greenville.

MLB Pipeline ranks him Boston’s No. 18 prospect. He has been listed as high as the Red Sox’ No. 8 prospect by Fangraphs in July 2024.

Jeremy Wu-Yelland, LHP

The 26-year-old lefty reached 98 mph with his fastball and held opponents to a .203 batting average in 23 starts during a breakout season in 2021.

But the 2020 fourth-round draft pick pitched just 4 innings total in 2022 and ‘23 combined after undergoing Tommy John surgery.

He was back up to 98 mph while throwing well out of the bullpen in 2025. He posted a 3.15 ERA, .201 batting average against and 37.6% strikeout percentage in 25 outings (45 ⅔ innings) for High-A Greenville and Double-A Portland. Thirty-four of those innings came with Portland.

Lefties with fastballs in the 90s and his type of strikeout ability are highly coveted.

Noah Song, RHP

The 28-year-old righty was a top prospect when Boston drafted him in 2019. But the United States Naval Academy graduate was assigned to flight school and missed three seasons while serving in the Navy.

The Phillies took a chance on him in the December 2022 Rule 5 Draft but he was returned to Boston in July 2023 as the Phillies could not afford to keep him on their 26-man roster when he returned from a back injury that he suffered that spring training.

He’s back in baseball shape now and his velocity increased during 2025 when he posted a 4.58 ERA in 31 outings (55 innings) across five minor league levels. He spent most of the year with Double-A Portland before a late-season promotion to Worcester.

It’s unlikely another team drafts him but there’s been great intrigue ever since the first-round talent dropped to the fourth round in 2019 simply because of the uncertainty over his military commitment.

Other Red Sox Rule 5 eligible players to watch: LHP Eduardo Rivera, IF Tyler McDonough, OF Allan Castro, OF Miguel Bleis.