Jul 23, 2026
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Read Article Red Sox vs. Mariners prediction: Seattle favored to win Sunday's MLB matchup [6/21/2026]
Updated: | First published:
Written by Jason Bevilacqua, Head of Content and Communities
Get Boston Red Sox vs Seattle Mariners predictions for MLB Sunday.
The Seattle Mariners will take on the Boston Red Sox in MLB action at T-Mobile Park on Sunday, starting at 4:10 PM ET.
The Mariners will start Logan Gilbert (5-4, 3.43 ERA), while the Red Sox have opted for Payton Tolle (3-4, 2.93 ERA).
Based on the latest simulation results, Dimers' advanced MLB model projects the Mariners as the most likely winner of the Red Sox vs. Mariners game.
This article offers further insights into Sunday's matchup, including best bets and picks.
Red Sox vs. Mariners prediction: Who will win and cover?
Using innovative machine learning and data, we have simulated the outcome of Sunday's MLB game between the Red Sox and Mariners, forming part of our MLB predictions coverage.
Our famous predictive model gives the Mariners a 55.1% chance of defeating the Red Sox.
According to our model, the Red Sox (+1.5) have a 63.7% chance of covering the run line, while the over/under total of 6.5 runs has a 55.7% chance of going over,.
Red Sox vs. Mariners odds [6/21/2026]
We have sourced the best MLB odds in America for this game, which are listed here:
| Bet Type | Red Sox | Mariners |
|---|---|---|
| Run Line | +1.5 (-200) | -1.5 (+188) |
| Moneyline | +113 | -126 |
| Total | o6.5 (-114) | u6.5 (+105) |
All odds are correct at the time of publication and are subject to change.
Red Sox vs. Mariners picks and best bet
After matching our predictions against the best current odds, we can reveal our picks for each of the major markets. Plus, find our best bet for the game below:
| Bet Type | Pick | Bet Now |
|---|---|---|
| Run Line | Mariners -1.5 | +188 |
| Moneyline | Mariners | -126 |
| Total | Over 6.5 | -114 |
According to our best MLB bets, the top play to make on this game is Over 6.5 total runs.
These picks are based on our probabilities matched against the implied probabilities from the sportsbook odds.
Red Sox vs. Mariners game-day updates and essential details
Sunday's MLB matchup between the Mariners and Red Sox at T-Mobile Park is scheduled to begin at 4:10 PM ET.
- Who: Boston Red Sox vs. Seattle Mariners
- Date: Sunday, June 21, 2026
- Time: 4:10 PM ET/1:10PM PT
- Venue: T-Mobile Park
Conclusion
We predict the Mariners, with a 55.1% win probability, will likely beat the Red Sox in Sunday's MLB matchup.
Additional tools and information for betting safely can be found in our Responsible Gambling hub.
Jason Bevilacqua, an expert in MLB, NHL, NBA, MLS, and NFL, delivers game previews, best bets, and props. Since 2020, as Head of Social and Community at Dimers, he has contributed insightful articles utilizing data-driven models and simulations.
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