Boston Red Sox vs Seattle Mariners Prediction, 6/21/2026 MLB Picks, Best Bets & Odds

Game: Boston Red Sox vs Seattle Mariners

Date: Sunday, June 21, 2026

Location: T-Mobile Park in Seattle, WA

TV: MLB.TV

Odds/Point Spread: Boston (+162) Seattle (-196)

T-Mobile Park is where the Seattle Mariners (39-38) will attempt to defeat the Boston Red Sox (30-43) on Sunday. The odds on this game have the Red Sox at +162 while the Mariners are coming in at -196. The over/under has been set at 8.5. The men taking the mound are Payton Tolle and Logan Gilbert.

As a unit, the Boston Red Sox are scoring 4.0 runs per contest, which has them at 29th in baseball. They have notched a total of 288 runs while holding a team on-base percentage of .312. The Red Sox have recorded 129 two-baggers as a squad and have knocked 62 balls out of the stadium. They have accumulated 276 RBI's in addition to 601 hits on the year, and their team batting average sits at .245. Boston is slugging .383 and have been called out on strikes 604 times, while being walked on 209 occasions.

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They have a strikeout to walk ratio of 2.78 and the pitching staff has earned a collective WHIP of 1.27. Red Sox pitchers have allowed 81 home runs in addition to 297 runs in total (5th in the league). Boston has allowed 600 hits (8.4 per 9 innings) and also 279 earned runs. The Red Sox have an earned run average of 3.90 over the course of the season (8th in the league), and the staff has rung up 612 batters. They have walked 220 opposing hitters and their FIP comes in at 4.00 as a unit on the campaign.

Red Sox relief pitchers have come into the game with runners on 60 times and also have had 60 appearances in high leverage situations. The relief pitchers have earned 35 holds on the year (19th in baseball). The Red Sox bullpen have a save percentage of 71.4% and stepped onto the hill in 57 save situations. They have recorded 15 saves on the campaign and have blown 6 of their 21 chances to save the game. The relief pitchers have inherited 89 runners this season with 31.5% of those players crossing home plate. The Red Sox have dispatched 223 relief pitchers to the mound this season.

The Red Sox have transformed 69.8% of baseballs in play into outs out of their 5,799 innings, which has them sitting 20th in pro baseball. The Boston Red Sox are sitting with 1,933 putouts at this point in the season, as well as 614 assists and 34 errors. Their fielding percentage is currently at .987 which has them sitting 14th in baseball, and have earned 44 double plays.

Tolle (3-5 career win-loss mark) sits with a FIP of 3.58 while he has gone up against 310 batters in the majors. He has surrendered 64 base knocks (7.8 hits per 9 innings) and has had 24 walks. His earned run average is 3.64 (30 ER's allowed) and his WHIP is 1.186. Tolle has taken the hill for 74 innings and has racked up 79 K's during his pro baseball career.

The Seattle Mariners have accounted for a team OBP of .314 and a team batting average of .234 so far this year. They have been rung up on 655 occasions (7th in the league) and have a total of 598 hits. Seattle has compiled 97 home runs for the season to go along with 313 runs batted in. The Mariners hold a team slugging percentage of .391 and they score 4.18 runs per contest (20th in the league). They have notched 98 two-baggers, while taking a walk 261 times as well as notching 322 runs.

The Mariners are sitting with a team WHIP of 1.184 and are the owners of a FIP of 3.60 as a team for the season. They are sitting at 17th in the league as a pitching staff in total hits given up with 615. The Seattle pitching staff have given up 303 runs this season while holding an ERA of 3.64 (277 earned runs allowed). Their strikeout to walk ratio is 8.80 (668 strikeouts vs 196 free passes). They have conceded 75 home runs and they relinquish 3.98 runs per 9 innings (5th in MLB).

They rank 22nd in MLB holding a save rate of 58.1%, and they have sent 231 relievers to the hill so far this season. Their bullpen pitchers have stepped onto the mound 86 times in high leverage situations and also on 58 occasions with base runners. Sitting with 74 save situations, the Mariners have 42 holds and 13 blown saves. Seattle has called on bullpen pitchers to take the mound in 31 save chances and they have walked away with 18 saves. Seattle relievers hold an inherited score percentage of 20.5% out of 78 inherited base runners.

The Seattle Mariners have turned 70 double plays and have a fielding percentage of .987 (11th in professional baseball). The Mariners have 618 assists, 34 errors and have earned a total of 2,055 putouts for the season. Out of their 6,165 innings played, the Mariners hold a defensive efficiency of 69.8% (18th in professional baseball).

In his pro baseball career, Gilbert has surrendered 772 hits while totaling 976 strikeouts in 921 frames. He has allowed a total of 365 ER's while earning a WHIP of 1.056 and having a FIP of 3.5. His K/BB ratio is 4.86 and he has faced 3,723 batters during his pro baseball career. Gilbert (52-40 career record) has a 3.57 earned run average while allowing 7.5 hits per nine innings.

Who will win tonight's MLB game against the spread or moneyline?

Guy Bruhn's Pick: Take Seattle (-196)

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