Mariners option RHP Gregory Santos to Tacoma, recall RHP Will Klein

Another season debut for the Mariners might be on the horizon

The Seattle Mariners announced Wednesday that they have optioned hard throwing RHP Gregory Santos to Triple-A Tacoma. In his place is another flamethrower, RHP Will Klein. Santos has struggled thus far in 2025, most notably having yet to record a single strikeout while still struggling with his command. Eight walks in seven innings pitched is difficult to stomach in the best of circumstances, but with no corresponding efficacy beyond his ability to manufacture ground balls, Santos seemed destined for a reset effort.

Additionally, returns to the bullpen from the injured list at or near the horizon like Troy Taylor and Matt Brash give Seattle options in the near term that should have high leverage capabilities.

Klein, meanwhile, has the look of a high leverage arm, albeit not yet the track record. The towering Eastern Illinois University product has had no shortage of free passes, issued both throughout his career and this year already with the Rainiers, but he has surefire swing and miss stuff, as well as the physique and track record to work multiple innings. Klein was claimed off waivers from the Sacramento Athletics after spending his early years with the Kansas City Royals, who traded him to the A’s in the Lucas Erceg deal. The A’s DFA’d Klein this off-season after he pitched just a couple of innings for the big-league club, and the Mariners—who have particularly targeted former Kansas City pitchers as second-chance acquisitions—were quick to pick him up. He spent his off-season training with Washington-based Driveline before being invited to spring training as an NRI. Klein will be making his Mariners debut if and when he pitches this road trip.