Seattle Mariners vs. Houston Astros Picks and Prediction, Sunday, September 21, 2025
Use Code WWWC On Sunday, the Seattle Mariners will face the Houston Astros at Daikin Park, and we have you ready to go with our Mariners vs. Astros prediction. First pitch from H-Town is at 7:10 p.m. ET.
Seattle is a -130 moneyline favorite, and the game total is eight runs scored.
The series is tied 5-5 over the last ten matchups between these AL West rivals, and the under was 5-4-1 in those games. If you want the Mariners vs. Astros prediction, read on and check out our MLB Predictions to beat the sportsbooks!
*Article published before the conclusion of Saturday's game.
Get Free $30 Credit for Premium Picks + Exclusive Discounts
Subscribe Now
Seattle is red hot and not slowing down
Seattle (85-69 SU, 67-87 RL, and 84-64-6 O/U) won two of three against Kansas City in its previous series. The Mariners are 9-1 in their last ten games (the over was 6-4).
Seattle will turn to right-hander Logan Gilbert on Sunday against Houston. In his last outing, the 28-year-old surrendered two runs and seven hits with five strikeouts in a 5.2-inning win versus the Royals. He is 5-6 with a 3.53 ERA and 1.05 WHIP in 23 starts (120.0 IP) this year, including 2-4 with a 5.08 ERA and 1.39 WHIP in 11 road outings (56.2 IP).
Seattle was among the most disappointing baseball teams last year, as it wasted a fantastic pitching rotation (2.85 ERA and a .205 OBA) with an inability to provide run support. The Mariners ranked 20th in runs scored in 2024, averaging 4.1 per game. Close losses were too common for M's fans, but they appear to have turned it around this year. Seattle has been more productive at the plate in 2025, ranking 11th in MLB in runs scored (4.73 per game), and has stayed competitive on the mound. Can they hold off Houston and win the AL West?
Seattle Mariners Baseball Injury Report: No new injuries for tomorrow's game against the Astros.
This is a crucial series for the Astros
Houston (84-70 SU, 75-79 RL, and 70-78-6 O/U) swept Texas in its previous series. The Astros are 6-4 in their last ten games (the under was 6-4).
Houston will start righty Jason Alexander on Sunday against the Mariners. In his last appearance (4.2 IP vs Texas), the 32-year-old gave up three runs (one earned) on five hits with five Ks. He is 4-1 with a 4.04 ERA and 1.30 WHIP in 16 outings (71.1 IP) this season, including 0-1 with a 4.93 ERA and 1.47 WHIP in eight appearances (34.2 IP) at Daikin Park.
Injuries forced the Astros to be creative last year, as they used 12 starting pitchers and 32 pitchers overall. Still, they turned their season around after a poor start to win their seventh American League West crown in the last eight years. Expectations are still high in H-Town, as the Astros are one game out of first place in the AL West. Can they sustain their success down the stretch to take down Seattle?
Houston Astros Baseball Injury Report: No new injuries to report for tomorrow's game against Seattle.
Mariners vs. Astros Pick
Moneyline Pick for Mariners vs. Astros
- Seattle ML (4 Units)
Gilbert held Houston to one run earlier this season and has held current Astros hitters to a .225 BA with a 25.9% K% and 29.4% Whiff%. He will lead the visitors to a win on Sunday, building off their recent surge of momentum. Alexander is not worth backing against a Seattle lineup that ranks third in road scoring (5.1 runs per game). He has an ERA of nearly five at home and has been homer-prone recently, surrendering seven long balls in his last six outings.
Bet on the Mariners ML on Sunday night!
Over/Under Pick for Mariners vs. Astros
- Under 8 (5 Units)
Houston ranks 25th in home scoring this season and is facing a big-time starter in Gilbert. They haven't fared well against him in the past, and I don't see why that will change tomorrow night. While the Mariners are a high-scoring squad on the road, their inexperience against Alexander (three combined previous plate appearances) could work against them. Both teams boast top-ten bullpens, as well. This is an important game for these ballclubs, which should result in a competitive, low-scoring affair.
Never Tried Winners and Whiners? Now Is Your Chance
- Get your first daily picks package for ONLY $1 using coupon code DOLLAR
- If the pick loses, we credit your account with 3 Flex Picks
- If the pick wins, we still give you 1 Flex Pick on the house
- Win or lose, you walk away ahead. One dollar. No catch.
- Check out more MLB predictions
Up To $1500 in Bonus Bets Paid Back if your First Bet Does Not Win
New Users – Bet $5 Get $200 in Bet Reset Tokens for 5 Days
