• The Mariners are -145 favorites vs the Red Sox
• Red Sox vs Mariners Over / Under today: 6.5 Runs
• Red Sox / Mariners TV Channel: NESN | MRTV

The Boston Red Sox (+118) visit T-Mobile Park to take on the Seattle Mariners (-145) on June 21, 2026. First pitch is scheduled for 4:10 pm in Seattle, WA.

This season, the Red Sox are 31-43 against the spread (ATS), while the Mariners are 30-48 ATS.

Red Sox vs Mariners Starting Pitchers Today:

• Red Sox starting pitcher: Payton Tolle 3-4, 2.97 ERA
• Mariners starting pitcher: Logan Gilbert 5-4, 3.42 ERA

Red Sox vs. Mariners Odds, Run Line, Over/Under & Moneyline

Red Sox vs Mariners Prediction for Today’s Game

Based on recent trends the model predicts the Mariners will win Sunday‘s MLB game with 55.9% confidence, factoring in game simulations, recent player performances, starting pitchers and injuries.

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We’ve highlighted some favorite MLB player prop bets for Red Sox players for Sunday‘s game, looking at profitable historical betting trends:

Best Red Sox Player Prop Bets Today:

• Caleb Durbin has hit the Home Runs Over in 3 of his last 8 games (+26.00 Units / 325% ROI)
• Ceddanne Rafaela has hit the Total Bases Over in 16 of his last 25 games (+11.65 Units / 44% ROI)
• Marcelo Mayer has hit the Singles Over in 16 of his last 25 away games (+10.45 Units / 41% ROI)
• Caleb Durbin has hit the Hits Runs and RBIs Over in 17 of his last 25 away games (+10.30 Units / 35% ROI)
• Marcelo Mayer has hit the Hits Over in 19 of his last 25 away games (+10.20 Units / 27% ROI)

And here are some favorite MLB player prop bets for Mariners players for Sunday‘s game, looking at profitable historical betting trends:

Best Mariners Player Prop Best Bets Today:

• Cal Raleigh has hit the Total Bases Under in 14 of his last 15 games (+12.90 Units / 57% ROI)
• Cole Young has hit the Runs Under in 21 of his last 25 games at home (+12.60 Units / 22% ROI)
• Julio Rodriguez has hit the Home Runs Over in 4 of his last 10 games at home (+10.80 Units / 108% ROI)
• Cal Raleigh has hit the Hits Runs and RBIs Under in 13 of his last 15 games (+10.80 Units / 60% ROI)
• Cal Raleigh has hit the Hits Under in 11 of his last 15 games (+10.50 Units / 70% ROI)

Red Sox Best Bets Today:

• The Boston Red Sox have covered the Run Line in 18 of their last 30 away games (+7.90 Units / 19% ROI)
• The Boston Red Sox have hit the 1st Five Innings (F5) Team Total Under in 27 of their last 45 games (+6.80 Units / 13% ROI)
• The Boston Red Sox have hit the Team Total Under in 27 of their last 45 games (+6.75 Units / 13% ROI)
• The Boston Red Sox have hit the Moneyline in 15 of their last 24 away games (+6.55 Units / 26% ROI)
• The Boston Red Sox have hit the Game Total Under in 24 of their last 45 games (+3.90 Units / 8% ROI)

Mariners Best Bets Today:

• The Seattle Mariners have hit the Team Total Under in 28 of their last 45 games (+9.30 Units / 18% ROI)
• The Seattle Mariners have hit the 1st Five Innings (F5) Team Total Under in 15 of their last 21 games at home (+9.00 Units / 35% ROI)
• The Seattle Mariners have hit the Game Total Over in 11 of their last 17 games (+5.65 Units / 30% ROI)
• The Seattle Mariners have hit the Moneyline in 8 of their last 12 games at home (+2.85 Units / 17% ROI)
• The Seattle Mariners have covered the Run Line in 11 of their last 24 games (+2.10 Units / 8% ROI)

Red Sox Against the Spread (ATS) Record

Against the spread this season, the Red Sox are 31-41 against the Run Line (-10.85 Units / -11.54% ROI).

• 31-43 when betting on the Moneyline for -20.75 Units / -23.04% ROI
• 33-38 when betting on the total runs Over for -9.05 Units / -11.1% ROI
• 38-33 when betting on the total runs Under for +1.45 Units / 1.78% ROI

Mariners Against the Spread (ATS) Record

Against the spread this season, the Mariners are 30-48 against the Run Line (-9.85 Units / -12.03% ROI).

• 39-39 when betting on the Moneyline for -12.2 Units / -11.49% ROI
• 38-37 when betting on the total runs Over for -2.5 Units / -2.91% ROI
• 37-38 when betting on the total runs Under for -4.6 Units / -5.37% ROI

Mariners vs Red Sox Home Run Prop Bets Today

Mariners vs Red Sox Total Hits Prop Bets Today

Mariners vs Red Sox Strikeout Prop Bets Today

Red Sox Keys to the Game vs. the Mariners

The Red Sox are just 0-39 (.000) when trailing entering the 9th inning this season — tied for lowest in MLB; League Avg: .055.

The Red Sox are just 2-23 (.080) when allowing 5 or more runs this season — lowest in MLB; League Avg: .207.

The Red Sox are just 1-6 (.143) when tied entering the 8th inning this season — 2nd lowest in MLB; League Avg: .500.

The Red Sox are just 31-43 (.419) this season — 5th lowest in MLB; League Avg: .500.

Mariners Keys to the Game vs. the Red Sox

The Mariners are just 6-19 (.240) vs bottom 10 scoring offenses this season Today, they face the Red Sox (29th in runs scored).

The Mariners are just 5-15 (.250) vs the top 10 runs allowed teams this season Today, they face Red Sox (seventh in runs allowed).

The Mariners are just 1-30 (.032) when trailing entering the 8th inning this season — tied for 5th lowest in MLB; League Avg: .104.

The Mariners are 45-38 (.542) vs the top 10 runs allowed teams since the 2025 season Today, they face Red Sox (seventh in runs allowed).

Red Sox Hitting Stats & Trends

The Red Sox are batting .185 on pitches out of the zone this season — 2nd best in MLB.

Red Sox hitters have an OBP of .334 (654 PA’s) against LHP this season — 4th best in MLB.

Red Sox hitters are slugging just .382 this season — 5th lowest in MLB.

The Red Sox are batting .268 against LHP this season — 3rd best in MLB.

Mariners Hitting Stats & Trends

The Mariners are batting just .207 against LHP this season — lowest in MLB.

The Mariners are batting just .296 on the first pitch of at-bats this season — 2nd lowest in MLB.

The Mariners are just 5-20 (.200) against the run line (-53.2% ROI) vs bottom 10 scoring offenses this season Today, they face the Red Sox (29th in runs scored).

The Mariners are just 6-19 (-58.3% ROI) vs bottom 10 scoring offenses this season Today, they face the Red Sox (29th in runs scored).

Red Sox Pitching Stats & Trends

Red Sox pitchers have walked 6% of batters when facing the leadoff batter in the inning this season — 3rd best in MLB.

The Red Sox have allowed 0.92 runs per game (68/74) in late innings this season — 2nd best in MLB.

Red Sox pitchers have induced opposing hitters to ground into just 36 double plays in 508 opportunities (7%) this season — 2nd lowest in MLB.

Red Sox pitchers have a strikeout rate of 28% in close and late situations this season — 2nd best in MLB.

Mariners Pitching Stats & Trends

Mariners pitchers have a first-pitch strike rate of 67% this season — highest in MLB.

Mariners pitchers have walked 7% of batters this season — best in MLB.

Mariners pitchers have walked 6% of batters when facing the leadoff batter in the inning this season — 2nd best in MLB.

Mariners pitchers have thrown at least two strikes in their first three pitches to 69% of opposing batters this season — highest in MLB.

More MLB Reading:

• Home Run Predictions Today
• Best NRFI Bets Today
• Strikeout Props Today
• MLB Starting Pitchers Today

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