Seattle Mariners vs Houston Astros Prediction, 9/21/2025 MLB Picks, Best Bets & Odds

Game: Seattle Mariners vs Houston Astros

Date: Sunday, September 21, 2025

Location: Daikin Park in Houston, TX

TV: Space City Home Network

Odds/Point Spread: Seattle (+132) Houston (-160)

Daikin Park is where the Houston Astros (84-69) will go up against the Seattle Mariners (84-69) on Sunday. The moneyline on this contest has the Mariners at +132 while the Astros are at -160. The betting total comes in at 8.5. The starting pitchers are George Kirby and Framber Valdez.

As a unit, the Seattle Mariners are putting up 4.7 runs/g, which has them at 10th in the league. They have 724 runs while holding a team on-base percentage of .320. The Mariners have earned 221 doubles as a team and have knocked 223 balls out of the stadium. They have 693 runs batted in and 1,271 hits this season, and their batting average is at .244. Seattle has a slugging percentage of .419 and have struck out 1,349 times, while taking a walk on 516 occasions.

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The Mariners hold a team earned run average of 3.91 on the campaign (14th in baseball), and the staff has struck out 1,334 batters. Mariners pitchers have given up 183 long balls in addition to 666 runs in total (17th in the league). They have walked 438 opposing hitters and their FIP sits at 4.04 as a squad for the year. Seattle has given up 1,272 hits (8.3 per 9 innings) in addition to 601 earned runs. They have earned a K/BB ratio of 3.05 and the pitching staff has earned a collective WHIP of 1.24.

The Mariners have dispatched 520 relievers to the hill so far this season. The relievers have inherited 138 base runners on the season and 25.4% of those players ended up scoring. They have tallied 41 saves this season and have missed out on 25 of their 66 chances to get a save. The Mariners relief pitchers have recorded a save percentage of 62.1% and have stepped onto the mound in 153 save situations. The bullpen have recorded 87 holds for the season (13th in baseball). Mariners relief pitchers have entered the game with runners on base 127 times as well as having 210 appearances in high leverage situations.

The Mariners have turned 70.1% of baseballs in play into outs in their 12,354 innings, which has them sitting 14th in pro baseball. The San Francisco Giants have earned 4,118 putouts so far this season, in addition to 1,278 assists and 66 errors. Their fielding percentage is at .988 which puts them in 7th in pro baseball, and have 111 double plays.

Kirby has taken the hill for 626 innings and has earned 604 K's so far in his pro baseball career. Kirby (44-33 record in his career) has earned a FIP of 3.57 and he has faced 2,559 hitters during his time in the major leagues. His earned run average is 3.62 (252 earned runs allowed) and he has a career WHIP of 1.118. He has conceded 608 base hits (8.7 hits per nine innings) and has 92 walks.

The Astros have a slugging percentage of .400 and they earn 4.26 runs per game (21st in the league). They have put up 234 doubles, while getting a free base 451 times and notching 652 runs. Houston has 169 HRs so far this season and 622 RBIs. They have struck out on 1,220 occasions (24th in baseball) and have recorded 1,308 base knocks. The Houston Astros are sitting with an on-base percentage of .318 and a team batting average of .252 so far this season.

The Astros have a team WHIP of 1.221 in addition to having a FIP of 4.00 as a unit over the course of the season. They currently have a K/BB ratio of 9.40 (1,428 strikeouts vs 480 free passes). They are sitting at 4th in baseball as a staff in total hits conceded with 1,185. They have conceded 185 homers and they give up 4.12 runs per 9 innings (8th in baseball). The Houston pitching staff have given up 625 runs on the season while holding an ERA of 3.83 (581 earned runs given up).

Houston bullpen pitchers have an inherited score rate of 22.7% of 172 inherited runners. Their bullpen pitchers have taken the field 166 times in high leverage situations and on 124 occasions with runners on base. Sitting with 152 save situations, the Astros have accrued 88 holds and also 16 blown saves. They sit at 2nd in baseball with a save percentage of 73.8%, and they have dispatched 488 relievers onto the field for the year. Houston has had relievers step onto the hill in 61 save chances and they have walked away with 45 saves.

The Houston Astros have turned 100 double plays and own a fielding percentage of .988 (8th in pro baseball). The Astros have racked up 1,207 assists, 66 errors and have a total of 4,092 putouts on the season. In 12,276 innings played, the Astros have earned a defensive efficiency of 70.7% (7th in the majors).

In his MLB career, Valdez has allowed 899 base knocks and he has 1,039 punch outs in 1,068 frames. Valdez (80-51 record in his career) holds a 3.35 ERA and has given up 7.6 hits per 9 innings. He has allowed 398 ER's while holding a WHIP of 1.200 and being the owner of a FIP of 3.3. He has a K/BB ratio of 2.71 and he has gone up against 4,429 hitters during his MLB career.

Who will win tonight's MLB game against the spread or moneyline?

Tony Sink's Pick: Take Seattle (+132)

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