Predictions, Where to Watch (9/18/25)

The Seattle Mariners play the final game of their three-game set with the Kansas City Royals this afternoon at Kauffman Stadium.

Seattle dropped yesterday’s game to Kansas City 7-5, after reliever Matt Brash blew a save in the eighth inning, surrendering four runs, including a two-run homer by former Mariner Adam Frazier.

With the Houston Astros winning last night, the Mariners slipped a half-game back in the AL West. They’re now tied with the Boston Red Sox for the second AL Wild Card spot, with the Cleveland Guardians lurking just 2.5 games behind.

The schedule ahead heightens the stakes. After today, Seattle heads straight to Houston for a pivotal head-to-head series against the Astros. They’ll then face the MLB’s worst team, the Colorado Rockies, before closing against one of its best, the Los Angeles Dodgers. By strength of schedule, the New York Yankees followed by the Mariners, have the easiest paths among AL Wild Card contenders, while the Red Sox face the toughest road.

Luis Castillo takes the mound for Seattle. He’s 9–8 with a 3.76 ERA, and after a brutal four-start stretch in August and early September (10.00 ERA), he’s steadied himself, allowing just two runs over 12 innings in his last two outings.

For Kansas City, Stephen Kolek gets the ball. Acquired from the Padres at the trade deadline, Kolek has been sharp in a Royals uniform, posting a 1.83 ERA across three starts (19.2 innings).

Prediction

The Royals’ bats have been lively this series, but Castillo has shown signs of regaining form. The Mariners should eke this one out in a lower-scoring battle.

Prediction: Mariners 3, Royals 2

Starting Lineups

Seattle Mariners

1. Randy Arozarena — LF

2. Cal Raleigh — C

3. Julio Rodríguez — CF

4. Josh Naylor — 1B

5. Jorge Polanco — DH

6. Eugenio Suárez — 3B

7. Dominic Canzone — RF

8. Leo Rivas — 2B

9. J.P. Crawford — SS

Starting Pitcher: Luis Castillo (RHP) — 9‑8, 3.76 ERA

Kansas City Royals

1. Mike Yastrzemski — CF

2. Bobby Witt Jr. — SS

3. Vinnie Pasquantino — 1B

4. Maikel Garcia — 3B

5. Salvador Pérez — C

6. Adam Frazier — LF

7. Jac Caglianone — RF

8. Carter Jensen — C

9. Michael Massey — 2B 

Starting Pitcher: Stephen Kolek (RHP) — 5‑5, 3.71 ERA 

How to Watch Mariners vs. Royals

First pitch for this afternoon’s Mariners-Royals game is set for 2:10 PM Eastern / 11:10 AM Pacific at Kauffman Stadium.

The game broadcasts on ROOTNW in Seattle and FanDuel Sports Network Kansas City locally. Out‑of‑market viewers can stream via MLB.TV. 

Seattle Mariners vs. Kansas City Royals

Date: Thursday, September 18, 2025

Time: 2:10 PM Eastern

Venue: Kauffman Stadium, Kansas City, MO

TV: ROOTNW, FanDuel Sports Network KC

Streaming: MLB.TV