Houston Astros vs Seattle Mariners Pick – 7/18/2025

The Houston Astros travel to T-Mobile Park to face the Seattle Mariners on Friday night in the opener of a three-game set between two AL West contenders. The Astros go into the second half of the season five games up on the Mariners in the standings. But the Mariners have been playing well and will look to pull closer in this game. Continue reading to get my Astros vs Mariners prediction for Friday night in the Pacific Northwest.

Our Astros vs Mariners Pick

• Pick: Seattle Mariners Moneyline
• Confidence: 3 stars
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Game Snapshot

• Matchup: Houston Astros vs Seattle Mariners
• Date & Time: Friday, July 18, 2025, 10:10 PM ET
• Starting Pitchers: Brandon Walter vs Luis Castillo
• Stadium: T-Mobile Park, Seattle, WA
• Broadcast: ROOT Sports NW, SCHN

Key Storylines

Pitching form

• Brandon Walter has a 1-2 record with a 3.98 ERA this season. He will have to be at his best to keep up with the starting pitcher on the opposite side.
• Luis Castillo is 6-5 with a 3.41 ERA. He has looked better as this year has continued and the Mariners would love for that to continue tonight.

Bullpen usage

Houston has the edge in the bullpen battle going into this series. The Astros rank third in the league in bullpen ERA this season. If they can overcome their starting pitching disadvantage in this game, the Astros could come back late.

Recent team streaks

• Houston went 1-4 in their final five games before the All-Star break.
• Seattle finished the first half of their season with a three-game sweep of the Detroit Tigers. They beat Tarik Skubal in one of those three wins.

Best Player Props

Betting Trends & H2H

• Seattle leads the season series between these teams by a 2-1 margin.
• Houston is 23-21 on the road for the season. Seattle is 25-21 at home.

Houston Astros vs Seattle Mariners Model Projection

Score Projection: Houston 4 – Seattle 5

Win Probability: Houston 48%, Seattle 52%

Final Thoughts

I think the starting pitching advantage for the Mariners will make a big difference in this game. Luis Castillo should put the Mariners on his back in this game to help them get a sixth straight win. Expect the Mariners to move to within four games of the Astros in the AL West standings by the end of Friday night’s action.

Jay Sanin

Jay Sanin is a sports bettor, writer and broadcaster from New York. He is an avid New York Knicks fan and is no longer ashamed to admit it. He is also an avid New York Giants fan, and is very ashamed to admit it. His top sports to handicap are the NBA, WNBA and men’s tennis for some reason. He has watched more UAlbany Great Danes basketball than anyone should consume.