Jul 22, 2026
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Read Article Reds vs. Mariners prediction: Seattle favored to win Tuesday's MLB matchup [7/21/2026]
Updated: | First published:
Written by Jason Bevilacqua, Head of Content and Communities
Get Cincinnati Reds vs Seattle Mariners predictions for MLB Tuesday.
The Seattle Mariners will take on the Cincinnati Reds, in what is expected to be a close MLB game, at T-Mobile Park on Tuesday, starting at 9:40 PM ET.
Luis Castillo (3-8, 4.93 ERA) will get the ball for the Mariners, while the Reds are going with Chase Burns (11-1, 2.54 ERA).
Based on updated simulation results, Dimers' proven MLB model gives the Mariners a slight edge with a 52.9% win probability over the Reds.
This article offers an expanded analysis of Tuesday's Reds vs. Mariners matchup, including best bets and picks.
Reds vs. Mariners prediction: Who will win and cover?
Using trusted machine learning and data analysis, we have simulated the result of Tuesday's MLB matchup between the Reds and Mariners, forming part of our MLB predictions coverage.
Our independent predictive model currently gives the Mariners a 52.9% chance of beating the Reds.
According to our model, the Reds (+1.5) have a 64.0% chance of covering the run line, while the over/under total of 7.5 runs has a 54.8% chance of going over,.
Reds vs. Mariners odds [7/21/2026]
We have sourced the best MLB odds in America for this game, which are listed here:
| Bet Type | Reds | Mariners |
|---|---|---|
| Run Line | +1.5 (-210) | -1.5 (+175) |
| Moneyline | +108 | -108 |
| Total | o7.5 (+100) | u7.5 (-102) |
All odds are correct at the time of publication and are subject to change.
Reds 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 in this matchup. Plus, find our best bet for the game below:
| Bet Type | Pick | Bet Now |
|---|---|---|
| Run Line | Mariners -1.5 | +175 |
| Moneyline | Mariners | -108 |
| Total | Over 7.5 | +100 |
According to our MLB best bets, the top play to make on this game is Over 7.5 total runs.
These picks are based on our probabilities matched against the implied probabilities from the sportsbook odds.
Reds vs. Mariners game-day updates and essential details
Tuesday's MLB game between the Mariners and Reds at T-Mobile Park is scheduled to start at 9:40 PM ET.
- Who: Cincinnati Reds vs. Seattle Mariners
- Date: Tuesday, July 21, 2026
- Time: 9:40 PM ET/6:40PM PT
- Venue: T-Mobile Park
Conclusion
We predict the Mariners, with a 52.9% win probability, will likely beat the Reds in Tuesday'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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