Astros vs. Mariners Prediction, Odds & Best Bets Tonight: Can Walter Stifle Seattle?

Brandon Walter has been mostly impressive during his first few starts for the Astros, and he'll be a challenge for Seattle.

Sean Tomlinson

Last Updated: July 18, 2025 7:10 PM EDT • 5 minute read

There's a monumental divisional matchup as we make our Astros vs. Mariners prediction for tonight.

The Astros lead the AL West while boasting the second-best record in the American League (56-40). The Mariners are five games back in the division and one game adrift of a wild-card spot.

The game opened as a near pick'em at our best MLB betting sites, but the home team has been steamed up quite a bit, and Seattle now sits as a -130 moneyline betting favorite. Our Astros vs. Mariners best bets have you all set up for first pitch at 10:10 p.m. ET (Root Sports) from T-Mobile Park in Seattle.

Astros vs. Mariners prediction: Astros to win (+108 via FanDuel) ⭐⭐⭐⭐
Best Astros vs. Mariners player props: Julio Rodriguez Under 1.5 total bases (-140 via bet365) ⭐⭐⭐⭐

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✅ Astros vs. Mariners prediction: Astros to win (+116 via FanDuel)

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There are benefits to making an early pick, as sometimes you're able to throw yourself at a rogue price from one of our best sports betting sites. That's the case here while making your Astros vs. Mariners prediction, with Houston backers getting plus-money odds from FanDuel.

It's the only such offering for your Astros vs. Mariners best bet for the World Series odds contenders, with the rest of the best sports betting apps listing the game at or near a pick 'em.

FanDuel is probably listing the Mariners as -126 betting favorites in part due to the presence of Luis Castillo on the mound for Seattle, giving the home side a notable pitching edge over Houston, with the Astros sending out Brandon Walter. The latter is making just his eighth big-league start.

But Walter has been shining, albeit in a small sample size.

He's endured two blowups with five-plus earned runs, though the always unfriendly pitching confines of Coors Field played a significant role in one. But he's allowed two or fewer runs in his other five outings, including a five-inning shutout during his first major-league start against the Tampa Bay Rays and their ninth-ranked offense.

His control has been sparkling, with a mere two walks given up across 40 2/3 innings, leading to a walk rate that sits in the top 1% of MLB. Walter's average exit velocity allowed rests in the 97th percentile, according to Baseball Savant, showing he's not filling the zone with cookies either.

💰 Best Astros vs. Mariners player props

✅ Best Astros vs. Mariners player prop: Julio Rodriguez Under 1.5 total bases (-140 via bet365)

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There's admittedly some risk here tied to a recent mini uprising from Rodriguez, who entered the All-Star break with home runs in three straight games and eight extra-base hits total over the final seven contests before heading off to Atlanta.

But look at both the larger sample size of Rodriguez's season and the pitching matchup he'll likely face for much of the night, and it becomes clear why fading him is the right play for our best Astros vs. Mariners player props.

Rodriguez isn't far removed from a month of June when he made more contact (.289 batting average), but his power was zapped, with an OPS that sat at .706 while logging just one home run. Remember, he also struggled immensely to start the season, with a .681 OPS in March and April.

That's who he's been this campaign, and his overall mediocre hard-hit rate of 45.4% (down significantly from 52% in 2023) reflects a harsh reality, as does a squared-up rate that sits in the 16th percentile.

Rodriguez has especially been struggling against the sort of spinning deception Walter leans on often. That includes slugging just .250 against cutters - Walter's most-used pitch, while throwing it 29.4% of the time.

📈 Astros vs. Mariners betting insights

Here are some betting insights from BetMGM in the hours before first pitch between the Astros and Mariners.

Home Run Derby winner Cal Raleigh is the second-most-bet player to hit a home run at +280
The Mariners are getting 62% of the bets and 59% of the handle on the moneyline
Currently, 73% of the money is going toward the Under on 7.5 runs, though 52% of the handle is on the Over
The Astros are receiving 61% of the money and 69% of the handle to cover +1.5 on the run line

💡 Expert MLB predictions

❓MLB betting FAQs

How do betting odds work?

Betting odds represent the probability of a specific outcome and determine how much money you can win on a bet. There are three main formats: American odds, Decimal odds, and Fractional odds. In the U.S., American odds are most common.

What is the run line in baseball?

The run line in baseball is a form of point spread betting unique to MLB. It typically sets a standard spread of 1.5 runs, meaning the favored team must win by at least two runs to cover the run line, while the underdog can lose by one run or win outright to cover.

What does moneyline mean in betting?

The moneyline in betting refers to a wager on which team or player will win the game outright, with no point spread involved. It’s the most straightforward type of sports bet—just pick the winner.

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Written by:
Sean Tomlinson

Sean Tomlinson has been in the sports media wilderness since 2009, and he joined Sportsbook Review in 2021. His work has been referenced in The New York Times and Forbes. He's also made appearances on The Fan 590 and TSN 1050. Sean is a regular bettor who places bets daily while using a handful of books. Most frequently, he uses FanDuel and bet365 due to the quality experience on those apps. While he'll often take an analytical approach, Sean enjoys the fun, recreational side of betting too, and embraces alternative markets on events like the Westminster Dog Show or Eurovision, or the many novelty props tied annually to the Super Bowl, for example. Beyond sports, Sean is also interested in the betting markets tied to politics, and especially those connected to American elections. He sees betting as a way to explore and engage in a deeper way, and takes that same view to his work. He plays poker periodically too, and is an avid fantasy sports player. Sean also previously spent time with Bleacher Report and theScore, all after earning his media studies degree from the University of Guelph-Humber.