Seattle Mariners probable pitchers & starting lineups vs. Houston Astros, April 8

Coming off a much-needed 4-3 win in the opener of a three-game set against the Houston Astros, the Seattle Mariners step into Tuesday night’s contest with a chance to secure their first series victory of the 2025 regular season.

The early schedule hasn’t been kind to Seattle. Through their first 11 games, the Mariners have faced fierce competition — 10 of those matchups have been decided by three runs or fewer. In a season already testing the team’s resilience, Monday night’s victory was much needed.

Playing their first game without the injured Victor Robles, who’s served as a firestarter at the top of the lineup, the Mariners had to rely on timely contributions elsewhere. Jorge Polanco returned to the lineup after a two-day absence due to side soreness, and reminded everyone why the Mariners hottest hitter is such a crucial piece to this offense. His go-ahead, two-run single in the bottom of the eighth flipped a 3-2 deficit into a 4-3 lead. That was all closer Andrés Muñoz needed to shut the door — helped by a vintage J.P. Crawford web gem that earned its own highlight reel.

Now, with momentum in hand, the Mariners are in position to take their second straight win. With a 6:40 p.m start time in T-Mobile Park let's take a look at tonight's probable lineups.

Probable Starters

For the Mariners: Luis Castillo, RHP (1-1, 3.00 ERA)

“La Piedra” takes the mound for his third start of the year and, as always, he brings his trademark steadiness. Castillo is the epitome of reliability in a rotation. He’ll give you five to seven strong innings, rack up some strikeouts, and he’ll unfortunately mix in a couple of untimely free passes. But what makes Castillo special is that when the lights are brightest, he often pitches his sharpest.

If you're trying to win your first series of the year, this is the guy you want leading the charge. Against a pesky Astros lineup, Castillo will look to keep hitters off balance, and set the tone early for a club that’s starting to show some grit.

For the Astros: Framber Valdez, LHP (1-1, 3.75 ERA)

Valdez isn’t just a top-tier arm — he’s one of the most accomplished left-handers in the league over the last few years. With three straight top-nine finishes in AL Cy Young Award voting and even some MVP votes to his name, he’s a pitcher that demands respect every time he's on the bump.

Against Seattle, Valdez has a complicated history. On paper, his 6-3 career record and 3.55 ERA versus the Mariners look solid. But dig deeper and you'll find recent cracks in that foundation. After dominating early matchups against Seattle in 2023 and 2024, the tide has shifted. Control issues have haunted him in his more recent outings — particularly in 2024, where he went 1-3 against the Mariners, including a couple of rough starts where the Seattle bats chased him out early.

The Mariners know how to grind out at-bats, especially against a pitcher who lives on breaking pitches and soft contact. If they can force Valdez into deep counts and capitalize on mistakes, they might just keep the momentum rolling.

Mariners Starting Lineup vs. Valdez

1. 3B Dylan Moore (R)
2. CF Julio Rodríguez (R)
3. DH Cal Raleigh (S)
4. LF Randy Arozarena (R)
5. C Mitch Garver (R)
6. 1B Donovan Solano (R)
7. RF Luke Raley (L)
8. 2B Ryan Bliss (R)
9. SS J.P. Crawford (L)

Astros Starting Lineup vs. Castillo

1. LF Jose Altuve (R)
2. 3B Isaac Paredes (R)
3. DH Yordan Alvarez (L)
4. 1B Christian Walker (R)
5. SS Jeremy Peña (R)
6. 2B Brendan Rodgers (R)
7. DH Yainer Diaz (R)
8. RF Cam Smith (R)
9. CF Jake Meyers (R)

How can I watch the Mariners today?

Regional Coverage

• Washington, Oregon, Idaho, Montana, Alaska: The game will be televised on ROOT Sports Northwest.​
• Texas, Louisiana, Arkansas, Oklahoma, and parts of eastern New Mexico: The game will be televised on Space City Home Network

Satellite Coverage

• Nationwide: Available via DirectTV

Radio Broadcast

• Seattle Region: Tune in to Seattle Sports 710 AM or stream the audio live at seattlesports.com.​
• Houston and other regions: Tune into KBME 790 AM/94.5 FM HD-2, TUDN 93.3/KLAT 1010

Streaming Options

• ROOT Sports Streaming App: Fans in Washington, Oregon, Idaho, Montana, and Alaska can stream the game live through the ROOT Sports streaming service
• FuboTV: Subscribers in the aforementioned regions can also stream the game live via FuboTV, which carries ROOT Sports Northwest
• MLB.TV: Out-of-market viewers can watch the game live with MLB.TV (subscription required)

Please verify local listings and streaming service availability to ensure access to the game in your area.

What’s at Stake?

It’s early April, sure. But in a stacked AL West, every series matters — especially against the reigning division champs. The Mariners have a chance to make a statement not just with the win, but with how they win. Monday showed they can scrap, battle, and come through in the clutch without all their pieces in place. Tuesday is about proving that wasn’t a fluke.