Mariners vs. Orioles Prediction, Odds, Probable Pitchers and Prop Bets for Tuesday, Aug. 12

Betting odds, pick and prediction for the Seattle Mariners-Baltimore Orioles matchup on Aug. 12.

Seattle Mariners starter George Kirby has led the Mariners to a 9-5 record in his starts this season. / Stephen Brashear-Imagn Images

After an off day on Monday, the Seattle Mariners are looking to extend their seven-game winning streak on Tuesday night against the Baltimore Orioles.

Seattle is just one game out of the top spot in the AL West, and it’s in a great spot to gain ground on either the Boston Red Sox (in the wild card race) or the Houston Astros (in the AL West) since the two teams face each other this week.

Seattle is favored on the road at the best betting sites with righty George Kirby on the mound on Tuesday. He’ll take on Baltimore’s Dean Kremer, who enters this start with a 4.35 ERA this season.

The O’s are in last place in the AL East and well out of the playoff race in the American League, but can they snap the Mariners lengthy winning streak?

Let’s dive into the odds, players to watch in the prop market and my prediction for Tuesday’s contest. 

Mariners vs. Orioles Odds, Run Line and Total

Odds via DraftKings Sportsbook

Run Line

• Mariners -1.5 (-105)
• Orioles +1.5 (-115)

Moneyline

• Mariners: -173
• Orioles: +141

Total

• 9 (Over -120/Under -101)

Mariners vs. Orioles Probable Pitchers

• Seattle: George Kirby (7-5, 4.04 ERA)
• Baltimore: Dean Kremer (8-8, 4.35 ERA)

Mariners vs. Orioles How to Watch

• Date: Tuesday, Aug. 12
• Time: 6:35 p.m. EST
• Venue: Camden Yards
• How to Watch (TV): MASN, ROOT Sports NW
• Mariners record: 66-53
• Orioles record: 53-65

Mariners vs. Orioles Best MLB Prop Bets

Mariners Best MLB Prop Bet

• Josh Naylor to Hit a Home Run (+370)

Earlier today, I shared in SI Betting's best home run picks – Daily Dinger – why Naylor is a prime target to go deep on Tuesday:

Seattle Mariners first baseman Josh Naylor was a massive trade deadline acquisition for the team, and he’s been on fire over the last week, hitting .500 with three homers in his last five games.

Now, Naylor has an ideal matchup on Tuesday night in Seattle’s series opener with the Baltimore Orioles. He’s taking on O’s right-hander Dean Kremer, who has allowed 18 home runs in 23 appearances this season posting a 4.35 ERA.

Naylor has dominated Kremer in his career, going 6-for-9 with one double, one homer and five runs batted in. On top of that, Naylor is hitting .291 against right-handed pitching with 11 of his 15 home runs this season. 

He’s a great bet at nearly 4/1 odds on Tuesday night. 

Mariners vs. Orioles Prediction and Pick

I’m buying the Mariners to keep their winning streak going against the O’s, who have dropped seven of their last 10 games and sold off some key veteran pieces at the trade deadline.

Baltimore is actually under .500 at home in the 2025 season, and it has struggled a bit in Kremer’s starts, going 9-14 straight up. 

The righty ranks in just the 51st percentile in expected ERA this season, and he’s well behind Kirby (71st percentile) in that statistic. The Mariners have also thrived in Kirby’s starts, going 9-5 overall and winning five of his six outings since July 1. 

It’s hard to fade the Mariners during this win streak, especially since they’ve won several of those games by multiple runs. 

Kirby has also found a groove after a slow start to the season, posting a 2.66 ERA over his last eight starts. He’s the superior pitcher in this game, and the Mariners have a lot more to play for in the playoff race than the O’s.  

Pick: Mariners Moneyline (-173 at DraftKings)

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Odds refresh periodically and are subject to change.

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