Mariners-Red Sox Series Preview: M’s look for rare feat in Boston

After getting swept in Toronto by the Blue Jays, the Seattle Mariners head into their next series looking to bounce back before hitting a favorable stretch to end the season.

But if history is any indicator, a quick turnaround will be a tall task to achieve.

Reports: Seattle Mariners to promote OF Lazaro Montes

The Mariners begin a three-game series against the Boston Red Sox on Monday at Fenway Park – a stadium that’s proven to be a challenging place for the M’s to play over the years.

Over their past 10 series at Fenway Park dating back to the 2015 season, the Mariners have won only one series, which came when they took two of three games from the Red Sox in April of last season. They’ve lost eight series during that stretch and tied one. Their record over those 10 series is 10-22.

Seattle lost two out of three games against Boston at T-Mobile Park in June. So, the Mariners would need to win all three games to take the season series, a feat they haven’t accomplished against the Red Sox since 2014.

Standings watch

The Mariners (64-73 record) entered Monday in third place in the American League West and five games behind the first-place Houston Astros. They trail the Cleveland Guardians by five games for the final AL wild-card berth.

The Red Sox (74-63) hold the second AL wild-card spot and are five games ahead of the Guardians. They trail the New York Yankees by four games for the top wild-card berth and the Tampa Bay Rays by 8 1/2 games for first place in the AL East.

Key Red Sox players

All-Star first baseman Willson Contreras is having a career year at the plate in his age-34 season. The right-handed slugger is batting .276 with a .906 OPS and 26 homers in 124 games. He entered Sunday leading MLB first baseman with a 152 wRC+ and 4.1 fWAR. All-Star center fielder Ceddanne Rafaela is also enjoying his best year at the plate, hitting .282 with a .764 OPS and 51 extra-base hits, including 16 homers, in 132 games. In addition to the breakout year offensively, Rafaela is one of baseball’s best defensive center fielders. The 2025 Gold Glove winner leads all center fielders with 20 defensive runs saved and is second with 15 outs above average.

Rookie left-hander Peyton Tolle is set to take the mound in Game 1 for Boston. Tolle is third among rookies with 141 strikeouts, fifth with a 125 1/3 inning pitched, and seventh among rookies who have made at least five starts with a 3.09 ERA. The Mariners will likely see right-hander Sonny Gray, an AL Cy Young candidate, during the series as well. The 36 year old has a 16-4 record and 2.82 ERA over 143 2/3 innings. His normal turn in the rotation would be Tuesday, but Boston has yet to announce its starter for that game.

Flamethrower Aroldis Chapman has continued to be one of baseball’s top closers at 38 years old. The left-hander’s 1.81 ERA is ninth and 31.2% strikeout rate 14th among MLB relievers with at least 40 innings pitched. He has converted 30 of 32 save attempts.

Big M’s debut expected

The Mariners are calling up slugging outfield prospect Lazaro Montes when rosters expand to 28 players Tuesday, per multiple reports. The news was first reported by Francys Romero.

Montes, who is ranked as the No. 56 prospect in baseball and fifth in the Mariners’ farm system by MLB Pipeline, is second among all minor leaguers with 38 this season.

If Montes joins the club on Tuesday as expected, he’ll become the third big-time prospect to reach the majors this year, joining shortstop Colt Emerson and starting pitcher Kade Anderson.

Injuries

Sunday provided some bad news on the injury front for the Mariners and some good news for the Red Sox.

Seattle placed starting pitcher Emerson Hancock on the 15-day injured list with a left adductor strain. The right-hander had been slated to start Wednesday’s series finale in Boston. The M’s have yet to confirm their starter the finale, but it will likely be right-hander Bryce Miller, who was moved to the bullpen Friday but has yet to pitch since. Miller last pitched on Aug. 23.

Meanwhile, outfielder Roman Anthony and shortstop Trevor Story each returned to Boston’s lineup from the injured list on Sunday. Anthony was sidelined for 100 games by a sprained right wrist. Story missed 92 games due to a sports hernia.

The Red Sox could also get utility infielder Isiah Kiner-Falefa (left forearm inflammation) back from the IL during the series, though he’s not expected to return until at least Tuesday when roster expand to 28 players, per MLB.com.

The Mariners could get some good injury news Monday when it comes to third baseman Brendan Donovan. The 29 year old was eligible to return from the 7-day concussion injured list Saturday. Manager Dan Wilson on Saturday said Donovan “doing better” and “getting much closer” to a return.

Reliver Cooper Criswell (right shoulder strain) is also nearing a return for the M’s. He made his third rehab appearance with Triple-A Tacoma on Friday, tossing 1 1/3 scoreless innings with one strikeout. Criswell, who spent the 2024 and ’25 seasons with Boston, last pitched in the majors June 8.

Game times, probable pitchers and broadcast info

• Monday, 3:45 p.m. – Mariners (George Kirby, 9-10 record, 4.02 ERA) at Red Sox (Peyton Tolle, 8-6, 3.09)

• Tuesday, 3:45 p.m. – Mariners (Bryan Woo, 9-9, 4.36) at Red Sox (TBD)

• Wednesday, 1:10 p.m. – Mariners (TBD) at Red Sox (Patrick Sandoval, 1-3, 4.20)

The Mariners Radio Network broadcast of all three games will stream free on the Seattle Sports app beginning with the pregame show (2:30 p.m. Monday and Tuesday, noon Wednesday). On terrestrial radio in the Puget Sound area, all games will be on Seattle Sports 710 AM. On TV, all games will be on Mariners TV.

Seattle Mariners news and more

• Seattle Mariners place Emerson Hancock on the 15-day IL
• Ex-Seattle Mariners OF Kelenic signs minor league deal with Yankees
• The Seattle Mariners’ top candidates for September callups

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