Seattle Mariners vs Colorado Rockies Picks and Predictions for Sunday, September 20th, 2026

The Seattle Mariners will finish their 3-game road series Sunday afternoon with a 3:10 PM matchup against the Colorado Rockies at Coors Field, and we're ready to go with our Seattle vs. Colorado prediction. Seattle enters Sunday 11 games below .500 and in fourth place in the American League West after dropping Saturday’s game. Colorado has struggled throughout the season, sitting more than 40 games below .500 and at the bottom of the National League West. The Rockies will try to secure the series win at home, while the Mariners look to bounce back and split the final 2 games.Read more about this Seattle vs Colorado prediction! Struggling with handicapping? Try our MLB Predictions!

Mariners look to bounce back

Seattle’s offense has struggled to produce consistently this season, posting a .232 batting average with 629 runs on 1,190 hits. The Mariners have recorded a .312 on-base percentage and a .381 team slugging percentage. Seattle’s pitching staff has performed better than its offense, but the Mariners still carry a 4.21 team ERA into Sunday’s game. Randy Arozarena leads Seattle with a .281 batting average, 26 home runs, and 76 RBIs. Josh Naylor has supplied a team-high 154 hits this season.

Bryce Miller started for Seattle on Saturday, allowing just 1 unearned run on 4 hits through 5.1 innings. Miller struck out 6 batters and walked 2 before leaving the game with the Mariners ahead. The Seattle bullpen struggled after Miller’s departure, surrendering 4 runs on 5 hits over the final 2.2 innings. Carlos Vargas and Jose Ferrer were each charged with 2 earned runs, while Ferrer took the loss after recording only 1 out.

Seattle recorded 8 hits Saturday, but the Mariners couldn't generate enough offense after scoring 3 runs over the first 5 innings. Cal Raleigh led the way with 2 hits, including a home run, and drove in 2 runs. Randy Arozarena also went deep, finishing with 1 hit, 1 RBI, and 1 run scored. Julio Rodriguez and Michael Arroyo added 2 hits apiece, but the rest of the Seattle lineup combined for only 2 hits in the loss.

Kade Anderson will start for Seattle on Sunday. Anderson enters the game with a 1-2 record, a 5.33 ERA, and a 1.42 WHIP through 25.1 innings. He has recorded 21 strikeouts while allowing 28 hits, 8 walks, and 4 home runs. Anderson has not worked deep into many games, meaning the Seattle bullpen could again play a significant role Sunday afternoon.

Key Injury Report for Seattle:

• Nick Davila RP 60-Day IL
• Matt Brash RP 60-Day IL
• Brendan Donovan 3B 7-Day IL
• Emerson Hancock SP 15-Day IL
• Luke Raley RF 60-Day IL

Rockies look to secure the series

Colorado has been productive offensively despite its poor overall record, recording a .255 batting average with 721 runs scored on 1,337 hits. The Rockies have posted a .324 on-base percentage and a .418 team slugging percentage. Pitching has been Colorado’s biggest weakness, as the Rockies enter Sunday with a 5.61 team ERA after allowing 899 runs. TJ Rumfield leads Colorado with a .302 batting average and 159 hits. Hunter Goodman has hit a team-high 38 home runs, while Jake McCarthy leads the roster with 83 RBIs.

Jose Quintana started for Colorado on Saturday, giving up 3 runs on 5 hits through 4 innings. Quintana allowed 2 home runs, struck out 2 batters, and walked 1 before turning the game over to the bullpen. Colorado’s relief pitchers were excellent, holding Seattle scoreless on just 3 hits across the final 5 innings. Nick Frasso worked 2 scoreless innings to earn the win, while Juan Mejia followed with 2 shutout innings. Brennan Bernardino closed the game with a scoreless 9th inning.

The Rockies finished Saturday’s victory with 9 hits and scored all 5 runs in the final 4 innings. TJ Rumfield led Colorado with 2 hits, 1 RBI, and 1 run scored. Cole Carrigg drove in 2 runs, while Jake McCarthy added 1 hit, 1 RBI, and 1 run. Connor Norby also recorded 2 hits and scored once. The Rockies did not hit a home run in the victory but took advantage of 3 Seattle errors and several opportunities with runners on base.

Tomoyuki Sugano will take the mound for Colorado in Sunday’s matchup. Sugano is 12-10 with a 5.49 ERA and a 1.36 WHIP through 142.2 innings this season. The right-hander has struck out 86 batters while allowing 160 hits, 34 walks, and 31 home runs. Sugano has allowed plenty of hard contact this year, giving the Mariners an opportunity to recover after scoring only 3 runs Saturday.

Key Injury Report for Colorado:

• Willi Castro 2B 10-Day IL
• Chase Dollander SP 60-Day IL
• Winton Herrera RP 60-Day IL
• McCade Brown SP 60-Day IL
• RJ Petit RP 60-Day IL

Seattle vs. Colorado Pick

• Seattle vs. Colorado Spread Pick

Seattle is the better overall team in this matchup despite Saturday’s disappointing loss. The Mariners have a clear advantage on the mound because Colorado owns a 5.61 team ERA and will start Sugano, who carries an ERA near 5.50. Seattle’s offense has been inconsistent, but Arozarena, Raleigh, Rodriguez, and Naylor give the Mariners enough capable hitters to take advantage of a struggling starter at Coors Field.

Anderson has not been dominant for Seattle, but Colorado’s pitching problems are much more severe. The Mariners should also be motivated to respond after their bullpen wasted Miller's strong performance on Saturday. Look for Seattle to score early against Sugano and build enough separation to cover the run line.

• Seattle vs. Colorado Over/Under Pick

The total for Sunday’s matchup is set at 11 runs, but both starting pitchers enter with ERAs above 5.00. Sugano has surrendered 31 home runs this season, and pitching at Coors Field will make it difficult for him to avoid additional damage. Anderson has also allowed more than 1 hit per inning and may not remain in the game long, putting pressure on a Seattle bullpen that gave up 4 runs Saturday.

Colorado has scored 721 runs this season and owns a respectable .418 slugging percentage, while its pitching staff has allowed 899 runs. Seattle should drive most of the offense against Sugano and the Colorado bullpen, but the Rockies can score several runs against Anderson. Expect both teams to create consistent scoring opportunities as this game climbs over the total.

• Pick: Over 11

Final Score Prediction: Seattle Mariners 8, Colorado Rockies 5