Cubs vs. Mariners Win Probability: Who Will Win Tonight’s MLB Game? (Saturday, Aug. 22)
LHP David Peterson and LHP Kade Anderson square off tonight in the second game of a three-game set as we break down the Cubs vs. Mariners win probability.
The Mariners have a 52% win probability on prediction market apps, but based on how well the Cubs have played since the All-Star break, I'm surprised it's not lower. First pitch from T-Mobile Park in Seattle is set for 7:15 p.m. ET (FOX, MLB.TV).
➡️ Follow all of our MLB analysis and expert predictions for the 2026 season.
🏆 Who will win Cubs vs. Mariners? Live MLB win probability
💰️ Kalshi promo code
Prediction market via Kalshi. You can use our Kalshi promo code for $35 in bonuses by signing up today. Market subject to change.
The Mariners have a 52% win probability, and more than $580,000 has already been traded in this market. Seattle originally opened with a 55% win probability Wednesday night, but money has come in on the Cubs as liquidity has increased. Yes contracts on the Mariners are available at 53¢, with more than $410,000 in liquidity at that price.
The Cubs have lost back-to-back games after a 6-5 setback in 10 innings in the first game of this series Friday. Third baseman Alex Bregman homered twice in the loss - a two-run shot in the first inning and a solo blast in the ninth to force extras. Outfielders Pete Crow-Armstrong and Ian Happ each added a solo homer in the first and eighth innings, respectively.
The Mariners bounced back Friday after dropping two of three games against the Brewers in Milwaukee from Tuesday to Thursday. Pinch runner Leo Rivas - he came in for designated hitter Taylor Ward in the eighth inning - hit a walk-off RBI single with two outs in the 10th. Catcher Cal Raleigh hit a three-run home run in the second inning.
My prediction: Cubs win (48¢). The Cubs are 20-13 since the All-Star break and haven't lost three in a row since June 7-10. While Peterson is having a down season, he has allowed one or fewer earned runs in four of his last six starts. For more MLB analysis, dive into Mike Spector's best home run predictions today.
📃 Affiliate disclosure
Sportsbook Review may receive a commission if you sign up through our links. Not intended for use in MA. Bonuses not applicable in Ontario. 21+ only. (Gambling problem? Call 1-800-GAMBLER)
⚾ Will there be a run in the first inning of Cubs vs. Mariners?
More than $14,000 in volume has cleared in this market, with traders projecting a 46% chance of a first-inning run. If you're looking to buy Yes contracts at 46¢, you can instantly get more than $23,000 filled.
The Cubs have had a first-inning run scored in 46% of their games, while the Mariners have seen a first-inning run in 53% of theirs. Peterson has not allowed a first-inning run in six of his last seven starts, and Anderson is making his MLB debut today.
My prediction: No run in the first inning (55¢). Peterson has been trending upward lately - he has a 2.55 ERA in August, compared to 5.29 on the season - and Anderson is MLB Pipeline's No. 5 prospect overall, so he will likely be able to get through one inning without giving up a run.
📊 Cubs vs. Mariners win expectancy
Win expectancy based on Kalshi percentages at time of publish.
| Team | Win expectancy | Opened | Movement |
|---|---|---|---|
| Cubs | 48% | 45% | ↑ 3% |
| Mariners | 52% | 55% | ↓ 3% |
📺 How to watch Cubs vs. Mariners
- Date: Saturday, Aug. 22
- First pitch: 7:15 p.m. ET
- Ballpark: T-Mobile Park (Seattle)
- TV: FOX
- Streaming: MLB.TV
- Cubs starter: David Peterson (7-7, 5.29 ERA)
- Mariners starter: Kade Anderson (MLB debut)
Related Articles
