M's flame throwing newcomer ready for breakout 2024

Relief pitcher Gregory Santos is an elite talent who could take another step forward in the Mariners' bullpen.

Seattle Mariners v Chicago White Sox
Seattle Mariners v Chicago White Sox / Michael Reaves/GettyImages
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Former White Sox and newly-minted Mariner flamethrower Gregory Santos toiled for a South Side team that failed to live up to expectations but don't blame the 24-year-old reliever. Santos has an electric skill set, including a sinking fastball he can hit up to triple digits and a devastating slider, one of the league's most brutal offspeed offerings.

Last season, Santos was in the upper echelon of WAR for relief pitchers (1.6), and most projection systems see continued success. ZIPS has Santos down for another 1-WAR season, which they usually earmark for the best of the best closers in baseball: guys like Edwin Diaz and Josh Hader.

The Dominican Republic-born Santos came into 2023 with a four-seamer and a slider, the typical reliever pitch mix. However, he scrapped the four-seam fastball for a two-seamer, and things took off from there. The exciting thing is Santos picked up the pitch mid-season. The new pitch mix helped Santos avoid barrels at an elite level (100%). Imagine what the Mariner's pitching lab can do to help him take the next step in 2024. The former White Sox play-by-play announcer, Jason Benetti, had glowing remarks when Seattle Sports Brock and Salk asked about Santos's upside.

"He's this kind of untapped mineral," Benetti said. "And you're talking about all the metrics that suggest he's going to have a breakout year, and I wouldn't disagree. I mean, he just completed his first season with a two-seamer. So the White Sox pitching coach Ethan Katz had him in San Francisco very early on when Ethan was the assistant there, and then Gregory ends up with the White Sox and Ethan converted his four-seam fastball to a two-seamer, and it was all about spin efficiency."

Jason Benetti on Gregory Santos

Santos ended 2023 on the injured list with some elbow inflammation, which could be a red flag for his future health. However, there is a good chance the White Sox shut him down to protect his arm because 66 innings was a career-high. Manager Scott Servais has a rotating bullpen, and both Andres Munoz and Matt Brash should help keep Santos fresh and healthy in 2024. That trio harkens back to the days of the Cincinnati Reds' Nasty Boys (Norm Charlton, Randy Myers, and Rob Dibble). The Mariners' new three-headed late-inning monster also stacks up with the Houston Astros' current backend lineup of Bryan Abreu, Ryan Pressley, and Josh Hader.

By the looks of it, we'll see some close games between the two-rivals, with Santos playing a key role in the Mariners getting over the hump.