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Mariners vs. Astros Dunkel MLB Picks, Predictions and Prop Bets - Sept. 21

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21 September 2025 By Data Skrive

The Seattle Mariners will try to keep a three-game win streak going when they visit the Houston Astros at 7:10 p.m. ET on Sunday. Logan Gilbert (5-6, 3.53 ERA) will start for the Mariners, who are 86-69 this season and first in the AL West. Jason Alexander (4-1, 4.04 ERA) is the expected starter for the Astros, who are 84-71 and second in the AL West.

Despite being the away team the Mariners are a moderate moneyline favorite (-141) over the Astros (+119). The game has an over/under set at 8 runs.

Mariners vs. Astros Odds, Game Time

Game day: Sunday, September 21, 2025
Game time: 7:10 p.m. ET
Location: Houston, Texas
Stadium: Daikin Park
Favorite: Mariners (-141)
Underdog: Astros (+119)
Over/under: 8

How to Watch Mariners vs. Astros

TV Channel: ESPN
Live Stream: Fubo (Watch for free)

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Mariners vs. Astros: Betting the Moneyline

The Mariners have gone 62-45 in games they were favored on the moneyline (winning 57.9% of those games).
Houston has been victorious in 32, or 58.2%, of the 55 contests it has been chosen as underdogs in this season.
Seattle has entered 56 games this season favored by -141 or more and is 36-20 in those contests.
This year, the Astros have won 15 of 23 games when listed as at least +119 or worse on the moneyline.
The Mariners have a 58.5% chance to win this contest based on the moneyline's implied probability.
The Astros have an implied victory probability of 45.7% according to the moneyline set for this matchup.

Mariners vs. Astros: Betting the Spread & Total

In the 155 games in which bookmakers have set an over/under for the Mariners, they have combined with opponents to go over the total 84 times (84-66-5).
Houston and its opponents have hit the over in 70 of its 155 games with a total this season.
The Mariners have put together a 67-88-0 record ATS this season.
The Astros are 78-77-0 against the spread in their 155 games that had a posted line this season.

Dunkel Index Prediction for Mariners vs. Astros

Pick OU: Over (8)
Prediction: Mariners 6 - Astros 4

Check out all the Dunkel Index MLB Baseball Picks!

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About the author

Data Skrive

Data Skrive creates sports articles about every player, on every team, in every league, for every game, for every fan. Data Skrive know sports. With over 100M monthly readers across 500+ websites and 200+ DMAs, their innovative Fan Engagement Solution creates engaging and entertaining sports content that fans value to drive revenue for their customers. Sports never stop, and covering every topic at the right time is not feasible. Data Skrive's technology is able to cover highly relevant topics that are interesting and engaging to your fans.