Seattle Mariners vs Houston Astros Prediction 9/20/2025 Today’s MLB Picks

In this article, we will formulate a Mariners vs Astros Prediction for this MLB game on Saturday, September 20th at the Daikin Park in the second game of this series, with the Mariners having the 1-0 lead. Let’s take a look at the prediction for this MLB matchup.

Houston Astros Preview

The Houston Astros have an 84-70 record this season and are sitting on the second place of the AL West. The Astros have a 46-33 home record and 70-78 in over/under. They are coming off a 0-4 home defeat by the Mariners, that ended their three-game winning streak. They are playing the Athletics and the Angels next.

The Astros have a .251 batting average this season, .317 OBP and .398 slugging percentage. Houston’s pitching staff has a 3.83 ERA and 1.22 WHIP. Jose Altuve leads the Astros with 148 hits, adding a team-high 26 home runs. Jeremy Pena is the team’s best hitter with a .303 batting average, while Christian Walker leads the team in RBI with 82. 

Framber Valdez (L) is the projected starting pitcher for the Astros, and he has a 12-10 record, 3.59 ERA and 1.22 WHIP.

Seattle Mariners Preview

The Seattle Mariners have an 85-69 record this season and are sitting on the second place of the AL West. The Mariners have a 37-42 road record and are 84-64 in over/under. They are coming off a 4-0 road victory over the Astros, and have six consecutive wins. Over is 6-4 in their last 10 games and are playing the Rockies and the Dodgers next.

The Mariners have a .244 batting average this season, .320 OBP and .420 Slugging percentage. Seattle’s pitching staff has a 3.989 ERA and 1.23 WHIP. Julio Rodriguez leads the Mariners in hits with 169, and he is the team’s best hitter with a .269 batting average. Cal Raleigh leads the team both in RBI with 118, and in home runs with 56.

George Kirby (R) is the projected starting pitcher for the Mariners, and he has a 9-7 record, 4.46 ERA and 1.23 WHIP.

Seattle Mariners @ Houston Astros Betting Trends: September 20, 2025

• Probable Starting Pitcher: Framber Valdez      Record this season: 12-10      ERA: 3.59
• Home Record: 6-3
• Last 5 against Mariners: 2-1

Why the Houston Astros will win

• The favorites have won each of the Mariners’ last 12 games.
• The Mariners have lost six of their last seven road games against AL West opponents following a win.
• The Astros have covered the run line in each of their last eight games following a loss.
• The Mariners have failed to cover the run line in nine of their last 10 road games against AL West opponents following a win.
• The Astros have led after 5 innings in eight of their last nine night games.
• The Mariners have lost the first inning in four of their last five games as road underdogs against American League opponents.
• The Astros have led after 3 innings in eight of their last nine night games.

• Probable Starting Pitcher: George Kirby      Record this season: 9-7      ERA: 4.46
• Road Record: 4-4
• Last 5 against Astros: 1-1

Why the Seattle Mariners will win

• The Mariners have won seven of their last eight games as underdogs against the Astros.
• The Astros have lost four of their last five games as home favorites against the Mariners following a loss.
• The Mariners have covered the run line in each of their last 10 games as underdogs against the Astros following a road win.
• The Astros have failed to cover the run line in each of their last eight games as home favorites against the Mariners following a loss.
• The Mariners have won the first inning in each of their last three games against AL West opponents.
• The Mariners have led after 3 innings in five of their last six road games.
• The Mariners have led after 5 innings in each of their last four games against AL West opponents.

Total Runs Facts

• Seven of the Mariners’ last eight games as underdogs have gone OVER the total runs line.
• Each of the last four 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 eight of the Mariners’ last nine games as road underdogs.
• The ‘Inning 1 UNDER 0.5 runs’ market has hit in seven of the Astros’ last eight games as home favorites against American League opponents.

Houston Astros Player Prop Facts

• Framber Valdez has recorded a win in three of his last four appearances against AL West opponents that held a winning record.
• Framber Valdez has recorded six or more strikeouts in each of his last five home appearances against AL opponents.
• Ramon Urias has hit a home run in two of his last three home appearances against AL West opponents.
• Ramon Urias has recorded at least one hit in each of his last 10 appearances with his team as a favorite against AL West opponents.
• Jeremy Pena ranks 6th amongst qualified players for Batting Average (.303) this season.

Seattle Mariners Player Prop Facts

• Julio Rodriguez has hit a home run in five of the Mariners’ last six road games against AL opponents that held a winning record.
• Randy Arozarena has recorded a Double in each of the Mariners’ last four games as underdogs against the Astros.
• George Kirby has recorded a win in six of his last seven road appearances against AL West opponents.
• George Kirby has recorded six or more strikeouts in four of his last five appearances against AL West opponents.
• J.P. Crawford has recorded at least one hit in each of the Mariners’ last eight games as underdogs against AL opponents.
• Cal Raleigh ranks 1st in the league in Home Runs (56) this season.

Matchup/League Facts

• The Astros rank 1st in the league for strikeouts this season (1438).
• The Astros rank 4th in the league for opponent batting average this season (.232).
• The Mariners rank 29th in the league for doubles this season (221).
• The Mariners rank 29th in the league for triples this season (9).

Mariners vs Astros Prediction

The Mariners are 3-1 in their last 4 head-to-head meetings against the Astros, but the Astros are 3-2 in their last 5 meetings in Houston. Under is 4-0 in their last 4 meetings in Houston.

In this Mariners vs Astros Prediction, both teams are coming at a pickem price. This is a huge matchup as both teams are fighting for the first place of the AL West, and I like the value with the home team in this one. Valdez has been elite at home for the Astros, with a 2.21 home ERA and has only one earned run in two starts against the Mariners this season. On the flip side, Kirby has been terrible on the road for the Mariners, with a 5.74 ERA, and was torched in his only start against the Astros this season, for 5 earned runs. Take the Houston Astros for a bounce-back win at home in this one.