MLB Prop Bets: Seattle Mariners vs Chicago Cubs (August 21, 2026)
The Chicago Cubs (74-54) face the Seattle Mariners (60-68) at T-Mobile Park on Friday at 10:10pm (ET). Let's take a look at the MLB Prop Bets for the matchup. Matthew Boyd is the probable pitcher for the Cubs, while Emerson Hancock is the probable pitcher for the Mariners. The Cubs opened as favorites but this has since changed, with the Mariners coming into -112 and Cubs drifting to -108. The total runs line is set at 8.0, with OVER at -105 and UNDER at -115.
- The Cubs (+155) have a 63-65 Run Line record this season, while the Mariners (-188) hold a record of 50-78.
- The Cubs have a 67-58-3 O/U record this season (meaning 67 games have gone over the total runs line, 58 have gone under and three have resulted in a push). The Mariners have a 63-57-8 O/U record.
Scoring Insights
- The Cubs are averaging 5.1 runs per game this season (2nd in the league). Comparatively, the Mariners are averaging only 3.9 (30th).
- In the field, the Cubs are allowing 4.3 runs per game this season (12th in the league), while the Mariners are allowing an average of 4.3 runs (T10th).
Let's take a look at how these teams perform in some other key statistical areas.
Batting Insights:
Batting Average
- Looking at their batting averages this season, the Cubs are at .248 (ranking 9th in the Major leagues), while the Mariners are batting .230 (29th).
Home Runs
- In terms of total home runs this season, the Mariners have hit 145 (16th in the Major Leagues). Meanwhile, the Cubs have managed 164 (8th).
Runs Batted In
- Finally, looking at their runs batted in, the Cubs have been outstanding this season, recording 617 RBIs to rank 2nd in the MLB. Comparatively, the Mariners have performed poorly in this area, recording only 483 RBIs to rank 30th.
Pitching Insights:
Earned Run Average
- The Mariners have an earned run average of 4.00 this season (11th in the Majors), while The Cubs have an ERA of 4.14 (17th).
Strikeouts
- Turning our attention to total strikeouts, the Cubs have recorded 982 this season, ranking 26th in the MLB. Meanwhile, the Mariners rank 12th for total strikeouts, recording 1085.
Opponent Batting Average
- Opponents are batting an average of .247 against the Mariners this season (20th in the Major Leagues). Comparatively, the Cubs' opponents are at .245 (17th).
First Innings Moneyline
- Here are their first innings moneyline records in 2026.
| Total | Home | Road | Favorite | Underdog | Neutral | Last 10 | |
|---|---|---|---|---|---|---|---|
| Cubs | 29-26-73 | 19-14-32 | 10-12-41 | 26-15-48 | 3-11-25 | 0-0-0 | 3-3-4 |
| Mariners | 30-33-65 | 17-14-31 | 13-19-34 | 25-23-51 | 5-10-14 | 0-0-0 | 5-3-2 |
Lead After Three Innings
The Cubs are -115 to lead after three innings, while the Mariners are -115.
- Here are their records after the first three innings in 2026.
| Total | Home | Road | Favorite | Underdog | Neutral | Last 10 | |
|---|---|---|---|---|---|---|---|
| Cubs | 47-42-39 | 30-19-16 | 17-23-23 | 40-25-24 | 7-17-15 | 0-0-0 | 2-3-5 |
| Mariners | 51-48-29 | 28-20-14 | 23-28-15 | 38-36-25 | 13-12-4 | 0-0-0 | 6-3-1 |
NRFI/YRFI
The NRFI market is paying -120 and the YRFI is paying -110.
- The NRFI is 70-58 in Cubs games this season. The Mariners have a 60-68 NRFI record.
Last Time They Met
The Mariners recorded a lopsided 14-6 victory against the Cubs at Wrigley Field when these teams last met on June 22, 2025. Donovan Solano was crushing the ball in that matchup, hitting 2 home runs and recording 5 RBIs.
