MLB Prop Bets: Boston Red Sox vs Seattle Mariners (August 31, 2026)
The Seattle Mariners (64-73) face the Boston Red Sox (74-63) at Fenway Park on Monday at 6:45pm (ET). Let's take a look at the MLB Prop Bets for the matchup. George Kirby is the probable pitcher for the Mariners, while Payton Tolle is the probable pitcher for the Red Sox. The Red Sox are favored to win at -167, while the Mariners are at +137. The total runs line is set at 8.0, with OVER at -107 and UNDER at -113.
- The Mariners (-156) have a 53-84 Run Line record this season, while the Red Sox (+129) hold a record of 67-70.
- The Mariners have a 68-61-8 O/U record this season (meaning 68 games have gone over the total runs line, 61 have gone under and eight have resulted in a push). The Red Sox have a 64-69-4 O/U record.
Scoring Insights
- The Mariners are averaging 3.9 runs per game this season (30th in the league). Comparatively, the Red Sox are averaging +0.6 more at 4.4 runs (16th).
- In the field, the Mariners are allowing 4.4 runs per game this season (14th in the league), while the Red Sox are allowing an average of 3.8 runs (5th).
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 Mariners are at .227 (ranking 30th in the Major leagues), while the Red Sox are batting .249 (7th).
Home Runs
- In terms of total home runs this season, the Red Sox have hit 138 (24th in the Major Leagues). Meanwhile, the Mariners have managed 157 (15th).
Runs Batted In
- Finally, looking at their runs batted in, the Mariners have recorded 511 RBIs to rank 30th in the MLB this season. Comparatively, the Red Sox have recorded 581 RBIs to rank 17th.
Pitching Insights:
Earned Run Average
- The Red Sox have an earned run average of 3.57 this season (4th in the Majors), while The Mariners have an ERA of 4.16 (16th).
Strikeouts
- Turning our attention to total strikeouts, the Mariners have recorded 1157 this season, ranking 13th in the MLB. Meanwhile, the Red Sox rank 11th for total strikeouts, recording 1168.
Opponent Batting Average
- Opponents are batting an average of .241 against the Red Sox this season (14th in the Major Leagues). Comparatively, the Mariners' opponents are at .249 (20th).
First Innings Moneyline
- Here are their first innings moneyline records in 2026.
| Total | Home | Road | Favorite | Underdog | Neutral | Last 10 | |
|---|---|---|---|---|---|---|---|
| Mariners | 33-37-67 | 20-16-32 | 13-21-35 | 26-25-52 | 7-12-15 | 0-0-0 | 3-5-2 |
| Red Sox | 30-39-68 | 18-17-31 | 12-22-37 | 21-25-47 | 9-14-21 | 0-0-0 | 1-3-6 |
Lead After Three Innings
The Mariners are +124 to lead after three innings, while the Red Sox are -160.
- Here are their records after the first three innings in 2026.
| Total | Home | Road | Favorite | Underdog | Neutral | Last 10 | |
|---|---|---|---|---|---|---|---|
| Mariners | 55-52-30 | 31-22-15 | 24-30-15 | 40-37-26 | 15-15-4 | 0-0-0 | 4-5-1 |
| Red Sox | 57-51-29 | 33-22-11 | 24-29-18 | 43-31-19 | 14-20-10 | 0-0-0 | 3-6-1 |
NRFI/YRFI
The NRFI market is paying -140 and the YRFI is paying +110.
- The NRFI is 62-75 in Mariners games this season. The Red Sox have a 66-71 NRFI record.
Last Time They Met
The Mariners recorded a 3-1 victory over the Red Sox at T-Mobile Park when these teams last met on June 21. Dominic Canzone went yard en route to that victory, hitting a home run to go with 2 RBIs. That result snapped the Red Sox's three-game winning streak against the Mariners.
