The Houston Astros host the Seattle Mariners in the second matchup of this three-game series at Daikin Park. MLB odds list Houston as a -115 favorite, while the total sits at eight.
My Mariners vs. Astros predictions target a side in this AL West contest.
Read on for my MLB picks for Saturday, September 20.
Mariners vs Astros prediction
Mariners vs Astros best bet: Houston Astros moneyline (-115)
Left-hander Framber Valdez takes the mound for the Houston Astros and should serve as a good candidate to back. Through 29 starts this season, Valdez is 12-10 with a 3.59 ERA and 1.22 WHIP.
His underlying metrics are equally impressive. Entering this matchup, Valdez ranks in the top half of the league in expected ERA (xERA), strikeout rate, and barrel rate.
This success is likely to continue against the Seattle Mariners. Through 18 meetings, Valdez is 7-3 with a 3.22 ERA and 1.28 WHIP.
From the other perspective, the current Mariners roster possesses a mere .237 expected batting average (xBA), .373 expected slugging percentage (xSLG), and .313 expected weighted on-base average (xwOBA) through 229 combined plate appearances against Valdez.
On the other hand, Seattle hands the ball to right-hander George Kirby. This season, Kirby ranks in the bottom half of the league in xERA, xBA, average exit velocity, and barrel rate.
Mariners vs Astros same-game parlay (SGP)
Due to these poor analytics, Kirby has surrendered three or more runs in two of his past three starts. These struggles are likely to continue against Houston, especially against Carlos Correa.
Through nine plate appearances against Kirby, Correa boasts a .375 batting average, .875 slugging percentage and .541 weighted on-base average.
Mariners vs Astros SGP
- Houston Astros moneyline
- George Kirby Over 2.5 earned runs
- Carlos Correa Over 0.5 RBI
Mariners vs Astros odds
- Moneyline: Seattle -105 | Houston -115
- Run line: Seattle -1.5 (+155) | Houston +1.5 (-190)
- Over/Under: Over 8 (+100) | Under 8 (-120)
Mariners vs Astros trend
Houston has won five of its past seven games. Find more MLB betting trends for Mariners vs. Astros.
How to watch Mariners vs Astros and game info
| Location | Daikin Park, Houston, TX |
| Date | Saturday, September 20, 2025 |
| First pitch | 7:10 p.m. ET |
| TV | RSNW, SCHN |
| Mariners starting pitcher | George Kirby (9-7, 4.46 ERA) |
| Astros starting pitcher | Framber Valdez (12-10, 3.59 ERA) |
Mariners vs Astros latest injuries
Mariners vs Astros weather
Odds are correct at the time of publishing and are subject to change.
Not intended for use in MA.
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