Seattle Mariners probable pitchers & starting lineups vs. Boston Red Sox, April 23

One of the main sentiments regarding last season's incarnation of the Seattle Mariners was that they never did enough to take advantage of a rotation which was statistically — and arguably just overall — the best in the Majors. This gave way to a concern that the team had missed a golden opportunity, with their fab five unlikely to repeat their high level of collective success in 2025.

Well, it's tough to argue with this opinion based on the early returns so far this year, with the Mariners rotation ranked 21st in ERA, along with 24th in both WHIP and opposing team batting average as of Wednesday morning. Logan Gilbert is looking like a true staff ace and Cy Young contender, but there are plenty of questions surrounding the other starters, including Bryce Miller.

It was a tough night at the office for Miller on Tuesday, as he allowed five hits, four walks and four earned runs in 4.2 innings and the Mariners lost 8-3, with concerns continuing about his right arm soreness. We're not even going to get into Trent Thornton, so let's look at the probable pitchers and starting lineups for Wednesday's game, with first pitch scheduled for 3:45 p.m. PT at Fenway Park.

Starting Pitchers

For the Mariners: Emerson Hancock, RHP (0-1, 12.71 ERA)

Emerson Hancock could not have gotten his 2025 campaign off to a more disastrous start against the Detroit Tigers, after being asked to step in for the injured George Kirby. While there have been games when he allowed more than the seven hits and six earned runs he gave up versus the Tigers, never before had he lasted less than one inning since debuting in the Majors during 2023.

As a result, Hancock was optioned to Triple-A Tacoma to work on his game (and confidence) before surprisingly being recalled and given his second start of the season in Cincinnati. There was a lot of understandable angst among Mariners fans, but he pitched a lot better as he only allowed five hits and two earned runs in 5.0 innings.

There is a growing narrative that the 25-year-old will never live up to the potential which saw the Mariners select him sixth overall in the 2020 draft, but it doesn't mean he can't still become a solid starter at the back end of a rotation. His sinker and changeup have been his two main pitches so far in 2025 and will be interesting to keep an eye on moving forward, given that last year he relied more on his four-seamer.

For the Red Sox: Sean Newcomb, LHP (0-2, 3.63 ERA)

Sean Newcomb is in a position that he hasn't been since 2018 in his second year in the Majors, as a regular starter in a rotation. The opportunity came about after multiple Red Sox pitchers went down injured during spring training, and he slotted in as the fifth starter.

This turn of fate allowed the 31-year-old to become the 28th Massachusetts-born pitcher to start a game in Red Sox history, although it turned into a rough outing as he allowed eight hits, two walks and four earned runs in 4.0 innings of a 8-5 loss to the Baltimore Orioles. He was a lot better in his second start against the St Louis Cardinals, before having another nightmare in his subsequent outing versus the Chicago White Sox.

Newcomb's most recent outing was his best yet in a Red Sox uniform, as he gave up four hits, two walks and no runs in 4.2 innings against the Tampa Bay Rays. The imposing southpaw's main weapon is his four-seam fastball and he has traditionally being effective at striking out batters, something which will provide an intriguing challenge for the Mariners lineup.

Mariners Starting Lineup vs. Newcomb

RF Dylan Moore (R)
CF Julio Rodríguez (R)
C Cal Raleigh (S)
LF Randy Arozarena (R)
DH Mitch Garver (R)
1B Donovan Solano (R)
3B Ben Williamson (R)
2B Leo Rivas (S)
SS J.P. Crawford (L)

Red Sox Starting Lineup vs. Hancock

LF Jarren Duran (L)
DH Rafael Devers (L)
3B Alex Bregman (R)
RF Wilyer Abreu (L)
SS Trevor Story (R)
1B Triston Casas (L)
2B Romy Gonzalez (R)
C Blake Sabol (L)
CF Ceddanne Rafaela (R)

How can I watch the Mariners today?

Regional Coverage

Washington, Oregon, Idaho, Montana, Alaska: The game will be televised on ROOT Sports Northwest.
New England outside of Fairfield County, Connecticut: The game will be televised on NESN.

Satellite Coverage

Nationwide: Available via DirectTV.

Radio Broadcast

Seattle Region: Tune in to Seattle Sports 710 AM or stream the audio live at seattlesports.com.
New England Region: Tune in to WEEI 93.7 or stream the audio live at audacy.com/weei.

Streaming Options

ROOT Sports Streaming App: Fans in Washington, Oregon, Idaho, Montana, and Alaska can stream the game live through the ROOT Sports streaming service
FuboTV: Subscribers in the aforementioned regions can also stream the game live via FuboTV, which carries ROOT Sports Northwest.
MLB.TV: Out-of-market viewers can watch the game live with an MLB.TV (subscription required).

What's at Stake?

The Mariners are on a streak of winning four consecutive series, including the two previous ones on the road, so they of course want to keep that sequence alive. For anyone worried after being dismantled on Tuesday night, this team has already displayed their mental fortitude in recovering from losing the first game in both Cincinnati and Toronto to take those respective series.

In addition, this is about proving they can win on the road versus an opponent which appears set to contend after meandering to a .500 record last season. The Mariners finished above the Red Sox in each of the past three years, but it sure looks as if the addition of Alex Bregman has helped rejuvenate Boston, as Seattle can attest to after his three-RBI game on Tuesday night.

From a historical standpoint, the Mariners have an all-time losing record of 82-141 at Fenway Park, and haven't won a season series on the road against the Red Sox since 2014. Finally, the M's need to find a way to win one of the next two games in Boston to secure a winning record on this nine-game road trip.

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