⚾ Astros vs. Mariners Prediction & Picks: MLB Odds for Saturday, April 11

The top two preseason favorites, and the last five combined AL West division champions meet in the second game of a four-game series, as the Houston Astros take on the Seattle Mariners. First pitch from T-Mobile Park in Seattle is set for 9:40 p.m. ET (ESPN Unlimited) with Lance McCullers Jr. opposing Luis Castillo. The Mariners are -145 betting favorites.

My Astros vs. Mariners prediction expects Castillo to lead Seattle to another important early season victory, despite one of Seattle’s best sluggers, Julio Rodriguez, continuing to struggle at the plate. I also add to my MLB picks my top home run prop play, and a three-leg same-game parlay that pays out juicy +834 odds.

⚾ Astros vs. Mariners picks & odds today

See all of our experts’ MLB picks based on the latest MLB odds; picks rated on a 1-to-5 star confidence scale based on betting value.

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🏆 Who will win Astros vs. Mariners?

Seattle has been one of MLB’s most disappointing teams with a 4-9 record and five-game losing streak entering this series. But its run differential only stood at -2 despite being five games under .500, which is a testament to its solid pitching and how good its offense can be when it clicks.

Score prediction: Mariners 5, Astros 3

💰 Astros vs. Mariners prediction & best bet

Mariners ML (-145)

Castillo has pitched to a career 3.02 ERA against Houston, his third-lowest ERA against any AL team (min. 3 starts). In three starts alone in 2025 against the division rivals, Castillo was brilliant with a 1.53 ERA over 17 ⅔ innings.

Five walks in that span led to a somewhat inflated 1.245 WHIP, and Houston entered the series leading the league with the third-highest walk rate. But I have confidence in Castillo finding the strike zone, as he has 219 walks in 764 ⅓ career innings at home versus 237 walks in 656 innings in road starts.

🔥 Best Astros vs. Mariners player prop bet

Julio Rodriguez Under 1.5 hits + runs + RBIs (-114)

Entering this series, Rodriguez had egregious career splits before and after the All-Star Break. Before the break, he is a career .257 hitter with a 23 home run per 162 games pace, a .317 on-base percentage, .409 slugging, and a 111 wRC+. After the break, his numbers improve drastically to a .297 average, 43 HR/162 games, .351 OBP, .552 slugging, and a 154 wRC+.

There isn’t a single pitch that Rodriguez has handled well yet this yet. He has seen fastballs at a 63.1% clip entering this series (his highest in a month in his career), and he is just 6-for-34 with 11 strikeouts in that split. However, he is also just 1-for-10 on a 22.9% breaking ball rate and 0-for-5 when seeing off-speed pitches 14% of the time.

💣 Astros vs. Mariners home run prediction

Randy Arozarena to hit a home run (+860)

Randy Arozarena is one of the few Mariners hitters with decent career success against Lance McCullers Jr., going 4-for-10 against him with a .855 OPS. 

Arozarena ranks in the top third in hard-hit rate and the 73rd percentile in average exit velocity, and is coming off a career high of 50.6% hard-hit rate a season ago.

I expect positive regression in the power department from Arozarena following his first home run yesterday, as his current 3.8 launch angle pales in comparison to his 11.3 or better in each of the last three seasons.

McCullers Jr. hasn’t allowed a home run in 11 innings this year, but is coming off a career-worst 1.6 HR/9 rate and 25.9% fly ball rate last year.

🚀 Astros vs. Mariners same-game parlay

Though there is a bit of pessimism with one leg of this same-game parlay by not expecting much offensively from Julio Rodriguez, there are still plenty of ways Seattle can overcome that to still earn a victory. Instead of adding Arozarena's home run prop to this parlay because of McCullers Jr.'s elite ground ball rate to this point, I am just banking on him to drive in a run of any kind. Given the value with the other two legs, this SGP still returns a decent payout.

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All MLB picks, including SGPs, have been tracked since March 26.

💡 How I'm betting Astros vs. Mariners: MLB strategy

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Neither McCullers Jr. nor Castillo have allowed a home run through two starts this season, which made it difficult to determine which lineup had the edge from a home run prop perspective. While Houston had five more long balls entering the series, Seattle's bullpen ranked in the top-10 with a 0.68 HR/9 rate, while the Astros bullpen allowed an MLB-worst 2.53 home runs per nine innings.

Thus, not only do I have more confidence in Seattle winning the game because of its ability to nail down the final innings, but Arozarena has just as good of a chance to homer in his at-bats against McCullers Jr. as he does the Astros relievers.

📊 Live Astros vs. Mariners odds

Seattle's moneyline odds have a wide range from -145 at the low end of the market to as high as -155. Yesterday's nine-run offensive breakout clearly instilled confidence in bettors, as the Mariners are attracting 70% of the moneyline wagers at DraftKings to this point.

All of the top sports betting sites are in unison with a total of 7.5 runs except bet365, who is at 8.0. Once again, 70% of the early wagers are backing the Over (perhaps as a reaction to last night's 15-run slugfest), so I wouldn't be surprised to see more sportsbooks align at an O/U of 8.0 before first pitch.

📈 Astros vs. Mariners betting trends

🚑 Astros vs. Mariners injuries

📺 How to watch Astros vs. Mariners

• Date: Saturday, April 11
• First pitch: 9:40 p.m. ET
• Ballpark: T-Mobile Park (Seattle)
• TV: ESPN Unlimited
• Streaming: MLB.TV
• Astros starter: Lance McCullers Jr. (1-0, 3.27 ERA)
• Mariners starter: Luis Castillo (0-0, 2.79 ERA)