The Seattle Mariners host the Tampa Bay Rays in the first matchup of this three-game series at T-Mobile Park.
My Rays vs. Mariners predictions are targeting the visitors at plus-money odds on the moneyline.
I explain why with my full MLB picks for Friday, August 8.
Rays vs Mariners prediction
Rays vs Mariners best bet: Rays moneyline (+110 at FanDuel)
The Tampa Bay Rays and Seattle Mariners are nearly identical in the hitting department, with both clubs averaging roughly 4.5 runs per game. The difference in tonight's matchup lies in the pitching, which favors Tampa Bay, as right-hander Drew Rasmussen takes the mound.
Through 22 starts this season, Rasmussen is 9-5 with a 2.81 ERA and 1.02 WHIP. His underlying metrics are equally impressive, as he ranks in the 72nd percentile or higher in expected ERA (xERA), walk rate, and barrel rate.
That success is likely to continue against Seattle, a team he has routinely dominated. Through four appearances against the Mariners, Rasmussen is 2-0 with a 0.61 ERA and 0.82 WHIP.
Meanwhile, Seattle hands the ball to Luis Castillo, who trails Rasmussen in every major metric. But it’s the advanced analytics that raise the biggest red flags.
Castillo ranks in the 37th percentile or lower in xERA, expected batting average (xBA), barrel rate, and hard-hit rate. He also owns a 4.91 ERA and 1.55 WHIP over his past two starts against the Rays.
Rays vs Mariners same-game parlay (SGP)
Rays moneyline
Luis Castillo Under 5.5 strikeouts
Brandon Lowe anytime home run
Continuing the Castillo fade, he ranks in the bottom half of the league in chase rate, whiff rate, and strikeout rate. Additionally, Tampa Bay’s Brandon Lowe has fared well against the right-hander.
Through 14 plate appearances, Lowe boasts a .583 slugging percentage and a home run.
Rays vs Mariners odds
Rays vs Mariners live odds
Rays vs Mariners opening odds
- Moneyline: Tampa Bay +120 | Seattle -140
- Run line: Tampa Bay +1.5 (-180) | Seattle -1.5 (+150)
- Over/Under: Over 7 (-120) | Under 7 (+100)
Rays vs Mariners trend
Tampa has won six of the past nine meetings between these teams. Find more MLB betting trends for Rays vs. Mariners.
How to watch Rays vs Mariners and game info
| Location | T-Mobile Field, Seattle, WA |
| Date | Friday, August 8, 2025 |
| First pitch | 9:40 p.m. ET |
| TV | FDSN Sun, RSNW |
| Rays starting pitcher | Drew Rasmussen (9-5, 2.81 ERA) |
| Mariners starting pitcher | Luis Castillo (8-6, 3.22 ERA) |
Rays vs Mariners latest injuries
Rays vs Mariners weather
Odds are correct at the time of publishing and are subject to change.
Not intended for use in MA.
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