Boston Red Sox
Starters: Woo, Gilbert, Kirby
The Red Sox hit .096 against Woo in 2025, who in 2 starts put up 13 innings, allowing only 2 earned runs and striking out 14. Gilbert struck out 10 in 5 innings in his only start, and Castillo managed a quality start despite giving up two home runs in his one matchup with Boston. Kirby and Castillo are both peaking around the same time, so either could start here, but Kirby’s precision might earn him the nod.
Kirby did not match up against the Red Sox this season, but if you look at his last 4 starts against them dating back to the end of 2023, he gave up a total of 4 runs in 4 games (22.2 IP).
Cleveland Guardians
Starters: Woo, Gilbert, Castillo
Here’s another American League Central opponent who avoided Woo. Gilbert, Castillo, and Kirby all pitched well against the Guardians in their two starts. No reason to shake up the pecking order. They’ve overtaken Detroit for the division lead and the likelihood of a matchup with the Mariners gets lower by the day.
Final Thoughts
Bryce Miller will most likely be the odd man out this post season. He has dealt with two injuries throughout the season and has not been as strong or consistent as the other four with an ERA in the mid 5s. The Mariners may very well bring 4 starters onto the postseason roster (maybe 5 if you count Emerson in the pen). Woo, Gilbert, Kirby, and Castillo will all be pitching in the postseason, opponent and splits-dependent.
At home, expect Bryan Woo, Luis Castillo, and Logan Gilbert on the mound. On the road, it could be more of a tossup and depend on the opponent. If the Mariners play Houston, give the rock to Kirby on the road. Otherwise, let’s stick with Bryan Woo, Luis Castillo, and Logan Gilbert.
Keep in mind, in years past, starters often end up in the pen and pitch in critical moments late into the games. If Kirby is not slotted to pitch for a series, you will likely see him coming out in one of the most important moments of a game.