How did Red Sox pitching prospect, top international signing Sadbiel Delzine fare in professional debut?

Red Sox pitching prospect Sadbiel Delzine missed most of his first professional season due to injury. When on the mound, though, the young right-hander showed flashes of intriguing potential.

As an amateur coming out of Venezuela, Delzine stood out thanks in part to his physical upside, power, and pitchability. Given those traits, the San Felix native drew a great deal of interest from teams — including the Red Sox — leading up to the start of the 2025 international signing period in January.

After celebrating his 17th birthday on January 9, Delzine officially signed with Boston for $500,000 on January 15. Not only did he receive the highest signing bonus of any Venezuelan pitcher in the 2025 international class, but that $500,000 also represents the most the Red Sox have doled out for an international pitcher since they landed Chih-Jung Liu out of Taiwan for $750,000 in October 2019.

Roughly five months after putting pen to paper, Delzine made his professional debut in the Dominican Summer League on June 3. He made three starts for DSL Red Sox Blue over the course of the next two weeks, posting a 4.82 ERA (2.75 FIP) with nine strikeouts to one walk across 9 1/3 innings in which opposing hitters batted .297 against him.

In the weeks following his June 17 outing against DSL Astros Blue (in which he pitched into the fourth inning for the first time as a pro), it was revealed that Delzine had been dealing with right flexor soreness. That ailment led to him being shut down for the remainder of the regular season, though he did return in time to make one playoff start that saw him allow one earned run on one hit, two walks, and one strikeout in his lone inning of work against DSL Athletics on August 26.

The overall body of work is obviously small, but Delzine was one of 31 Red Sox minor-leaguers to throw at least nine regular-season innings in the Dominican Summer League this year. Among those 31, he notably ranked first in groundball rate (64.3 percent), walk rate (2.6 percent), swinging-strike rate (30.8 percent), FIP, and xFIP (3.26), seventh in strikeout rate (23.1 percent), and 10th in WHIP (1.29), per FanGraphs.

“If he’d qualified, Delzine would be right there with Kendry Chourio and Kevin Defrank in the conversation for the best pitching prospect in the DSL,” Baseball America’s Josh Norris wrote on Tuesday. “Alas, an injury limited him to just 9 1/3 innings in the regular season before he re-emerged during postseason play.”

Already, Delzine is listed at 6-foot-5 and 198 pounds, though he is likely even bigger. The imposing righty primarily operates with an upper-90s mph fastball that has reached 96 mph. He also features a mid-80s gyro slider, a low-80s curveball, a mid-80s changeup, and an upper-80s cutter.

“At his best, Delzine showed a loose arm and a projectable body already capable of generating upper-90s velocity with his fastball,” Norris continued. “He backed it with a nasty curveball in the 79-84 mph range and a slider that came in a few ticks hotter. The heat was there when he returned to the mound, but the command of his pitches and synchronization of his body was a bit off-kilter.”

Delzine is currently regarded by Baseball America as Boston’s No. 25 prospect, which ranks 12th among pitchers in the organization. Barring a trade or other surprise move by the Red Sox this winter, he will likely begin his age-18 season by making his stateside debut in the rookie-level Florida Complex League next summer.