Seattle Mariners Reliever Has Setback as Bullpen Takes Another Hit

The Mariners shut Santos down earlier in the spring after he reported some discomfort near his teres major muscle. While he resumed throwing, the issue popped up again on Monday and a subsequent MRI revealed the mild strain. The Santos injury news isn’t ideal, but Seattle should have enough depth to overcome an absence of a few weeks.

Gregory Santos Will Miss Opening Day

Despite having a deep bullpen and an ability to turn waiver claims into quality arms, the Mariners gave up assets to the Chicago White Sox to acquire Santos. In exchange for the 24-year-old, Seattle dealt prospects Prelander Berroa, Zach DeLoach, and a Competitive Balance (Round B) draft pick. Santos broke out in 2023, tossing 66 1/3 innings with a 3.39 ERA (132 ERA+) while finishing 17 games and picking up five saves. Santos was one of the hardest throwers in MLB by averaging 98.8 mph on his sinker (which ranked in the 98th percentile).

Despite throwing hard, Santos recorded strikeouts at a slightly below average clip. However, Santos made up for this and had a great season by producing elite rates in other metrics. No qualified pitcher missed barrels at a better rate than Santos did last season. Additionally, he missed bats, got hitters to chase his pitches, and induced weak contact. He also excelled at minimizing walks (85th percentile) and using the sinker to generate ground balls (87th percentile).

2023 was Santos’ first full season in the majors. His previous career-high in MLB appearances was three in 2021 with the San Francisco Giants. While some might not want to give up a lot for a reliever with just one good season, the Mariners are also adding five years of club control. If Santos continues his production, the deal could be a steal for Seattle.

Other Injured Mariners Pitchers

Santos joins Matt Brash as an important M’s reliever to start the season on the injured list due to a spring injury. Brash’s injury seemed significant at first, but he recently started throwing again and shouldn’t miss as much time as initially anticipated. Furthermore, Seattle added Jackson Kowar in the Jarred Kelenic deal as a reclamation project. The former Kansas City Royals first-round pick has a good changeup and decent upside, but has struggled to put it together in the majors. While the Mariners have had success in getting the best out of arms like Kowar, he will miss the entire season after undergoing Tommy John surgery.

As the organization learned last year, every win matters and elite relievers go a long way in winning close games. While the Santos injury isn’t as bad as it could be, it’s still a tough blow for Seattle.