The Seattle Mariners continue to fight for a spot in the AL Wild Card race, but they’ll need to go through a tough Chicago Cubs team this weekend to make up ground.
The Cubs enter the contest as the +104 road dog, but I believe that their electric offense will give them the edge in my Cubs vs. Mariners predictions and free MLB picks for Friday, Aug. 21.
Who will win Cubs vs Mariners today: Cubs (+101)
The Seattle Mariners are banking on Emerson Hancock to have a big night on the mound, but the Chicago Cubs won’t make it easy on him.
Hancock relies heavily on his four-seamer, which he throws nearly 40% of the time. Chicago ranks eighth in SLG (.481) against that pitch from righties this month, and third in BB/K (0.90).
Matthew Boyd has not been quite as good as Hancock, but his matchup is preferable. The Mariners rank last in team average (.215) and SLG (.339) against left-handed pitching, and 29th in wOBA (.286).
Chicago is great value up to -105 tonight.
COVERS INTEL: Boyd throws his changeup more than a quarter of the time, and that’ll be the key vs. Seattle. The Mariners own a .190 average (29th) and .237 wOBA (26th) vs. left-handed changeups.
Cubs vs Mariners Over/Under pick: Over 7.5 (-117)
Hancock is having a great season, but the Cubs own the second-best offense in MLB (5.13 runs per game), and they could be his kryptonite.
Hancock sits in the 31st percentile in hard-hit%, but has managed to hold a respectable 1.1 HR/9. However, the ball might not stay in the yard against the Cubs, who are one of the best home run-hitting clubs in baseball (164 HR; 8th).
Boyd will also be susceptible to Seattle’s bats – he has a 6.16 ERA over his last three starts, and Chicago has cashed the Over in each of those outings.
I’m taking the Over up to -125.
Cubs vs Mariners home run prediction: Pete Crow-Armstrong (+309)
Pete Crow-Armstrong is having another fantastic season with 31 dingers, already equal to last year’s output, while ranking in the 99th percentile in batting run value and 89th percentile in barrel %.
PCA has gone yard four times in his last four contests, and he matches up well against Hancock. The Cubs slugger has nine dingers against right-handed four-seamers this season, tied for the ninth most in the majors.
- ML/RL bets: 8-5 +2.06 units
- Over/Under bets: 6-7, -1.42 units
Cubs vs Mariners weather
T-Mobile Park is expected to see overcast skies, with temperatures dropping as low as 71 degrees. Wind will not be a factor tonight.
Cubs vs Mariners odds
- Moneyline: Cubs +104 | Mariners -108
- Run line: Cubs -1.5 (+163) | Mariners -1.5 (-170)
- Over/Under: Over 7.5 (-117) | Under 7.5 (+113)
Cubs vs Mariners trend
The Cubs have hit the moneyline in 22 of their last 30 away games (+13.65 Units / 38% ROI). Find more MLB betting trends for Cubs vs Mariners.
How to watch Cubs vs Mariners and game info
| Location | T-Mobile Park, Seattle, WA |
| Date | Friday, Aug. 21, 2026 |
| First pitch | 10:10 p.m. ET |
| TV | Mariners.TV, Marquee Sports Network |
| Cubs starting pitcher | Matthew Boyd (8-2, 4.02 ERA) |
| Mariners starting pitcher | Emerson Hancock (7-7, 3.30 ERA) |
Cubs vs Mariners latest injuries
Odds are correct at the time of publishing and are subject to change.
Not intended for use in MA.
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