Victor Robles and 4 Mariners who will make or break the 2025 season

RHPs Gregory Santos and Matt Brash

In 2024, the Mariners bullpen was somewhere between just OK and not good enough. It did rank ninth with a 3.71 ERA, but was only 15th in FIP at 3.91.

In fairness, the Mariners entered last season thinking Santos and Brash were going to be a dynamic setup duo for closer Andrés Muñoz. Yet both were laid low by injuries, with Santos making only eight appearances and Brash making none as he missed the year recovering from Tommy John surgery.

Cut to now, and Santos is good to go and Brash is progressing better than expected. The latter made a surprise appearance in the Mariners' final Cactus League game on Monday, striking out two of the three batters he faced.

“After I struck out the second guy I was like...I don’t know what happened,” Brash said, again per Stockmar. “I kind of just took it all in. I’m back.”

The sheer promise of having these two pitchers back for most of 2025 — Brash likely won't return until late April or early May — is huge. Santos was nearly impossible to square up (i.e., 100th percentile barrel rate) for the Chicago White Sox in 2023, while Brash has fanned 32 percent of the batter he's faced as a big leaguer.

All pitchers are volatile, however, and that is doubly the case with relievers. And if the injury bug bites Santos and/or Brash again, the bridge to Muñoz is going to be just as rickety as it was in 2024.