Seattle Mariners vs Houston Astros Prediction 9/21/2025 Today’s MLB Picks

The Seattle Mariners and Houston Astros meet Sunday in MLB action at Daikin Park. Here’s a Seattle Mariners vs Houston Astros Prediction. This article will include a Seattle Mariners vs Houston Astros Pick.

Seattle Mariners Betting Preview

The Seattle Mariners are 86-69 on the year and play the Rockies and Dodgers next. The Seattle Mariners are batting .245 on the season, have a .320 OBP, and a .420 slugging percentage. The Seattle Mariners pitching staff has a 3.89 ERA and a 1.23 WHIP. Julio Rodriguez leads the Seattle Mariners with 170 hits and 94 RBI, while J.P. Crawford and Cal Raleigh have combined for 287 hits and 173 RBI.

Logan Gilbert gets the ball for the Seattle Mariners, and he is 5-6 with a 3.53 ERA and 164 strikeouts this season. Gilbert is 5-4 with a 3.48 ERA and 69 strikeouts in his career against the Houston Astros.

Houston Astros Betting Preview

The Houston Astros are 84-71 on the year and play the Athletics and Angels next. The Houston Astros are batting .252 on the season, have a .317 OBP, and a .398 slugging percentage. The Houston Astros pitching staff has a 3.85 ERA and a 1.22 WHIP. Jose Altuve leads the Houston Astros with 150 hits and 74 RBI while Jeremy Pena and Yainer Diaz have combined for 283 hits and 130 RBI.

Jason Alexander gets the ball for the Houston Astros, and he is 4-1 with a 4.04 ERA and 60 strikeouts this season. This will be Alexander’s first career game against the Seattle Mariners.

Seattle Mariners @ Houston Astros Betting Trends: September 21, 2025

• Probable Starting Pitcher: Jason Alexander      Record this season: 4-1      ERA: 4.04
• Home Record: 0-1
• Last 5 against Mariners: –

Why the Houston Astros will win

• The Astros have won four of their last five games as home underdogs against American League opponents following a loss.
• The Mariners have lost six of their last eight games as road favorites against AL West opponents following a road win.
• The Astros have covered the run line in eight of their last nine games as underdogs following a loss.
• The Mariners have failed to cover the run line in nine of their last 11 road games against AL West opponents following a road win.

• Probable Starting Pitcher: Logan Gilbert      Record this season: 5-6      ERA: 3.53
• Road Record: 2-4
• Last 5 against Astros: 2-2

Why the Seattle Mariners will win

• The Mariners have won each of their last 12 games as favorites.
• The Astros have lost each of their last five night games against AL West opponents following a home loss.
• The Astros have failed to cover the run line in each of their last 10 Sunday night games at Daikin Park.
• The Mariners have covered the run line in each of their last six games as favorites.
• The Astros have trailed after 5 innings in six of their last eight games as home underdogs against American League opponents.

Total Runs Facts

• Eight of the Mariners’ last 10 night games against American League opponents have gone OVER the total runs line.
• Four of the last five games between the Mariners and Astros at Daikin Park have gone UNDER the total runs line.
• The ‘Inning 1 OVER 0.5 runs’ market has hit in each of the Astros’ last six games.
• The ‘Inning 1 OVER 0.5 runs’ market has hit in each of the Mariners’ last five night games against American League opponents.

Houston Astros Player Prop Facts

• Jeremy Pena has hit a home run in two of the Astros’ last three home games.
• Jose Altuve has recorded at least one hit in 18 of his last 19 appearances against the Mariners after playing the previous day.

Seattle Mariners Player Prop Facts

• Logan Gilbert has recorded seven or more strikeouts in each of his last 13 appearances with the Mariners as favorites against AL West opponents.
• Logan Gilbert has recorded a win in three of his last four appearances at Daikin Park.
• Cal Raleigh has hit at least one home run in three of the Mariners’ last five games as favorites.
• Jorge Polanco has recorded at least one Double in five of the Mariners’ last six games as favorites against AL West opponents.
• Julio Rodriguez has recorded at least one hit in each of the Mariners’ last eight night games.

Matchup/League Facts

• The Astros rank T26th in the league for steals this season (77).
• The Astros rank 26th in the league for walks this season (453).
• The Mariners rank 3rd in the league for home runs this season (228).
• The Mariners rank 3rd in the league for walks allowed this season (440).

Seattle Mariners vs Houston Astros Prediction

The Astros are 11-1 with Alexander since getting him from the Athletics, and he’s allowed just 14 hits and 4 earned runs in his last 16.2 innings. It’s hard to argue with that sort of success. However, the Mariners have lost one game since September 6, and they’re in the driver’s seat in the AL West. Sometimes a team just catches a hot streak and there’s nothing you can do about it. The M’s have caught fire at the right time, and I’m not excited to step in front of it. Give me the Mariners.