Mariners vs. Rays Prediction, Odds, Probable Pitchers and Prop Bets for Monday, Sept. 1

Betting odds, pick and prediction for the Seattle Mariners-Tampa Bay Rays matchup on Monday.

Seattle Mariners catcher Cal Raleigh is a solid prop target on Monday. / Ken Blaze-Imagn Images

The Seattle Mariners are just two games out of the top spot in the AL West, and they’re slight favorites at the best betting sites for their matchup against the Tampa Bay Rays on Monday night.

Tampa Bay has fallen out of the playoff picture in the American League, but it could play spoiler to a Mariners team that has a small lead over the Texas Rangers for the final wild card spot in the AL.

Shane Baz (5.19 ERA) is on the mound for Tampa Bay against former All-Star Luis Castillo (3.75 ERA).

Here’s a breakdown of the odds, players to watch in the prop market and my prediction for Monday's action.  

Mariners vs. Rays Odds, Run Line and Total

Odds via DraftKings Sportsbook

Run Line

• Mariners -1.5 (+140)
• Rays +1.5 (-172)

Moneyline

• Mariners: -115
• Rays: -105

Total

• 8.5 (Over -114/Under -106)

Mariners vs. Rays Probable Pitchers

• Seattle: Luis Castillo (8-7, 3.75 ERA)
• Tampa Bay: Shane Baz (8-11, 5.19 ERA)

Mariners vs. Rays How to Watch

• Date: Monday, Sept. 1
• Time: 7:35 p.m. EST
• Venue: George M. Steinbrenner Field
• How to Watch (TV): FDSSUN, ROOT Sports NW
• Mariners record: 73-64
• Rays record: 67-69

Mariners vs. Rays Best MLB Prop Bets

Mariners Best MLB Prop Bet

• Cal Raleigh to Hit a Home Run (+260)

Despite a recent slump, Raleigh is an interest target to hit a home run on Monday, something I shared in today’s Daily Dinger – our best home run bets at SI: 

Seattle Mariners catcher Cal Raleigh has 50 home runs in the 2025 season, but he has found himself in a bit of a slump as of late, hitting just .119 over the last 14 days – although he has homered three times during that stretch.

The All-Star has a great chance to get back on track against Tampa Bay Rays righty Shane Baz, who has become one of the more home-run prone pitchers in MLB.

Baz has given up 26 homers in 26 appearances while posting a 5.19 ERA this season. Not only that, but he allowed seven homers in five starts in the month of August.

Raleigh has homered 30 times against right-handed pitching this season, and his recent slump has given us a pretty favorable number for him – +260 – on Labor Day. He’s worth a look to break out of his slump in this matchup. 

Mariners vs. Rays Prediction and Pick

Castillo hasn’t had his best season in 2025, but he’s still led the Mariners to a 15-12 record in his starts and has put together an expected ERA of 4.40. He struggled in August (6.66 ERA), but I still think the veteran right-hander is the pitcher to back in this matchup.

Baz has an ERA over 5.00 this season, and the Rays are just 13-13 in his outings – and they’re just one game over .500 at home in 2025. Like Castillo, Baz struggled in August, posting a 7.92 ERA in five starts, leading the Rays to a 1-4 record.

I don’t love to see Baz fading down the stretch, as the young starter may be running out of gas over the final stretch of the regular season.

Seattle has a lot more to play for in this matchup, so I’ll trust Castillo to rebound from his struggles last month. 

Pick: Mariners Moneyline (-115 at DraftKings)

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Odds refresh periodically and are subject to change.

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