Mariners vs. Phillies Prediction, Odds, Probable Pitchers and Prop Bets for Monday, Aug. 18

Iain MacMillan | Aug 18, 2025

Ranger Suarez and the Phillies are home favorites against the Seattle Mariners on Monday night. / Katie Stratman-Imagn Images

The Philadelphia Phillies have a firm grasp on the NL East, holding a five-game lead over the New York Mets. With that being said, if they want to catch the Milwaukee Brewers for the top spot in the National League, they need to string together some wins in a hurry.

They'll face the Seattle Mariners in an interleague series to start the week. Seattle is sitting 1.5 games back from the Houston Astros for the AL West lead, but is currently sitting in a wild-card spot. They can ill afford to lose their momentum in the final month of the season.

Mariners vs. Phillies Odds, Run Line, and Total

Odds via FanDuel Sportsbook

Run Line

• Mariners -1.5 (+152)
• Phillies +1.5 (-184)

Moneyline

• Mariners -104
• Phillies -112

Total

• Over 8 (-102)
• Under 8 (-120)

Mariners vs. Phillies Probable Pitchers

• Seattle: Logan Gilbert, RHP (3-4, 3.31 ERA)
• Philadelphia: Ranger Suarez, LHP (8-6, 3.28 ERA)

Mariners vs. Phillies How to Watch

• Date: Monday, August 18
• Time: 6:45 p.m. ET
• Venue: Citizens Bank Park
• How to Watch (TV): ROOTNW, NBCSP, MLBN (out-of-market only)
• Mariners Record: 68-57
• Phillies Record: 71-53

Mariners vs. Phillies Best MLB Prop Bet

• Ranger Suarez OVER 5.5 Strikeouts (-105) via BetMGM

The Mariners have the fourth-highest strikeout rate against left-handed pitchers this season, striking out on 24.9% of their plate appearances. They also have a strikeout percentage of 24.5% since the All-Star Break, which is also the fourth-highest rate. With that in mind, let's back Ranger Suarez to record at least six strikeouts in this game.

Mariners vs. Phillies Prediction and Pick

I'm hesitant to bet on the Mariners based on how they've played lately. They have the worst batting average in the Majors since the All-Star Break at just .221. They're also just 26th in OPS in that time frame at .683, compared to the Phillies, who come in at seventh in that stretch of time at .757. Even if you look at some more advanced metrics, the Mariners are 19th in wRC+ since the pause in action.

The pitching matchup in this game is largely a wash with Logan Gilbert (3.31 ERA) taking on Ranger Suarez (3.28 ERA). The offensive advantage the Phillies hold in this one is enough for me to back them as slight favorites at home.

Pick: Phillies -112 (via FanDuel)

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