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Red Sox vs. Mariners Series Preview

A look at the four-game set at Fenway against the Mariners.

Houston Astros v Seattle Mariners Photo by Abbie Parr/Getty Images

SB Nation Blog

Lookout Landing

The opponent in one sentence

The Mariners were presumed to be one of the worst teams in the American League coming into this year as they are still in the midst of a rebuild, but they may have arrived early judging by a hot start to the season.



Head-to-head record



Up. The Mariners have been trending up pretty much for the entire season, but they’ve been playing even better of late against some good competition. Their last two series were against the Astros and Dodgers, two preseason division favorites, and they won two of three from Houston before splitting a two-game set against LA. Given how the latter has started this year, splitting two games with them is a bonafide achievement.

Pitching Matchups

4/22: Nick Pivetta vs. Justin Dunn, 7:10 PM ET (MLB Network for out of market)

The Red Sox turn to one of their back-end starters to begin this series against the Mariners, though to his credit Pivetta has at least put up results better than many (myself included) expected. The righty has a solid 3.68 ERA on the year, and most impressive about his performance to this point has been his ability to keep the ball in the yard. That has been the biggest issue for Pivetta over his career, but he’s allowed just one long ball in his first three starts. The sample is small, though, so it’s hard to say it’s very sustainable. And he could be in trouble if those homers to start showing up, because he’s had a tough time keeping runners off the bases due to a high walk rate. I’ll be looking for how well he’s able to avoid barrels against a hot Mariners lineup.

On the other side, the Red Sox are going up against Justin Dunn, which could be a familiar name to those from the Boston area as he was a standout at BC and former first-round pick. The 25-year-old righty has not had a chance to pitch a ton in the majors, making 16 starts across three seasons in his career. It’s been a bit of a strange run, too, as his 4.06 ERA looks solid until you see the 6.37 FIP and wildly unsustainable .162 BABIP. This season he has more walks than strikeouts through two starts but still boasts a 3.72 ERA. Look for the Red Sox to take advantage of traffic on the bases and make him pay for walks in a way he really hasn’t had to over his short career. Dunn will feature a fastball in the low-to-mid 90s as well as a curveball and a slider.

Chicago White Sox v Boston Red Sox Game 2 Photo by Kathryn Riley/Getty Images

4/23: Martín Pérez vs. Yusei Kikuchi, 7:10 PM ET

Pérez has struggled a bit for the Red Sox, though he’s been picked up by his offense a bit to mask some of the issues. The lefty has an ugly 5.93 ERA to start the year through three starts, which is almost two runs worse than his FIP. It’s a small sample size so these kinds of disparities are not a big surprise, though it’s a troubling trend for someone like Pérez who is supposed to go in the opposite direction. When he’s at his best, he’s never going to miss a ton of bats nor will he be a control artist. The southpaw’s best quality is his ability to induce weak contact, which in theory should produce results that are better than his FIP. He’s currently allowing a .349 batting average on balls in play, and I’ll be looking to see how hard the contact he’s allowing on Friday will be.

Kickuchi was a relatively big signing out of Japan for the Mariners a few years ago. Granted, we’re not talking Shohei Ohtani or Yu Darvish type hype, but he is a solid mid-rotation starter that the Mariners were able to bring into their own rotation. He’s struggled a bit to find his footing in the majors, though the early returns in 2021 suggest he may be on his way to figuring things out. He’s got solid strikeout stuff, but the command can be a little inconsistent and it will show up both in the form of walks as well as hard contact. It’ll be all about getting to the southpaw early and not letting him get away with mistakes before settling into a groove. The Red Sox have been ultra-aggressive at the plate this season, and that kind of approach should be helpful against this kind of starter. Kikuchi will pitch mainly off his cutter while also mixing in a mid-90s fastball and a slider.

4/24: Nathan Eovaldi vs. Chris Flexen, 1:10 PM ET (MLB Network for out of market)

Eovaldi has been the biggest positive for the Red Sox rotation this year, as he’s giving them that consistent performance teams have been waiting for out of the righty for years. The big fastball that has been his hallmark forever is still there, but it’s really about everything else right now. En route to his 3.04 ERA through four starts, he has started to throw a lot more breaking balls, with both a slider and a curveball being added to the mix. Along with that fastball, a cutter and a splitter, that’s now five pitches for a guy who used to just try and blow heat by everyone he faced. That didn’t work, but so far this is. Eovaldi is striking out over a batter per inning while walking only 1.5 per nine, showing an elite ability to control the zone.

Flexen is back in the majors this season after heading over to Korea to pitch in the KBO last year. His performance there in which he struck out over 10 batters per nine with a 3.01 ERA was enough to earn him a major-league deal in Seattle after flaming out with the Mets prior to that. Still only 26 years old, the righty has been solid to start this season with a 3.38 ERA. There’s nothing he’s been doing spectacularly well, but he misses a decent number of bats, keeps his walk rate at a manageable level, and keeps the ball on the ground enough to not get killed by the long ball. Given his lack of track record in the majors, it would seem to me that the key is to get to him early, because these kinds of jack-of-all trades pitchers generally are the type to settle into a groove if they get through a couple easy innings. Flexen will feature a low-90s fastball along with a cutter, a curveball and a changeup.

4/25: Eduardo Rodriguez vs. TBD, 1:10 PM ET (MLB Network for out of market)

More than any other start this season, Rodriguez came out in his last outing against the Blue Jays looking like his 2019 self. The southpaw did give up a couple of homers, but that’s not the end of the world when you’re not walking anyone and really not giving up any hits. They were both solo homers and the only two runs against him on the day. Beyond that, his changeup looked as good as it did all year, and the command on all of his pitches was there. Now it’s all about building on that and being consistent in that ability. He’s been good all year, but if the Red Sox are going to sustain this hot start they need a dynamic starter or two. Eovaldi is there right now, but with his health always being a question Rodriguez being able to be that 2019 version of himself on a consistent basis would be a gamechanger.

The Mariners haven’t yet announced a starter for this series finale on Sunday. Nick Margevicius would be lined up to make the start, and he’s a lefty who has served as a swing man with mostly middling results. Last time I speculated on a TBD starter, though, I was wrong, so I won’t spend too much energy guessing here.

Toronto Blue Jays Vs Boston Bruins At TD Garden Photo by Jim Davis/The Boston Globe via Getty Images

Old Friends


Notable Position Players

Mitch Haniger is one of two hitters who has really served to carry this Mariners lineup so far in their hot season. Hitting right at the top, the outfielder is not going to put up the prettiest plate discipline numbers but he can hit the crap out of the ball when he sees a mistake. As a leadoff hitter, he gives Seattle a chance to jump out to early leads each and every day.

Ty France hits right behind him in that lineup and has also been off to a scorching start. He’ll draw a few more walks than Haniger, but he’s a similar kind of hitter in that he’ll strike out a bit but also will hit for big-time power and just generally smack hard contact all over the field.

Kyle Lewis is the reigning AL Rookie of the Year, but he’s yet to play this year. He’s been activated off the injured list, though, and will make his 2021 debut this weekend at Fenway.

Kyle Seager is a long-time member of this Mariners team, and while his numbers are not the same as they were in his prime, he’s still a threat to hit one out every time, particularly against right-handed pitching.

Evan White is a different kind of first baseman with a skillset built around defense and contact rather than power. He’s off to a tough start at the plate this season though.

Taylor Trammell is another top prospect in this Mariners outfield and he is about as boom or bust as it comes, possessing big power along with a strikeout rate over 40 percent.

Dylan Moore has been drawing a ton of walks, but it hasn’t been enough to pull his overall production out of the mud as he’s just not hitting for the kind of power to support a strikeout rate in the 30s.

J.P. Crawford is a former top prospect who can play good defense at shortstop but the bat has just never caught up.

Luis Torrens will play a lot behind the plate this weekend and his inability to impact the baseball has dragged down his offense so far this year.

Bullpen Snapshot

Rafael Montero is one of three guys who are leading what has been a surprising bullpen. Any of the three can get saves, and Montero has the most so far with three. He hasn’t missed as many bats as his stuff may suggest so far, and the results could catch up soon if he doesn’t start to strike out more batters.

Kendall Graveman has been the best reliever on this roster. A former back-end starter for the A’s, he’s been thriving in relief with good control and more than a strikeout per inning.

Keynan Middleton is the former Angels closer who is coming back from some injury issues. He’s struggling a bit so far this year, though, failing to miss bats while also suffering from some inconsistent control.


James Paxton just can’t catch a break with his health. He’s going to have to undergo Tommy John surgery and will miss all of this season and likely a chunk of 2022 as well.

Ken Giles is recovering from Tommy John himself and signed a two-year deal with the Mariners last winter. He won’t contribute this year but could be their closer in 2022.

Shed Long Jr. hurt his shin late last season and is still dealing with those issues. His timeline to return is unclear.

Jake Fraley hurt his hamstring early in this season and has been out ever since, though his return shouldn’t be too far off at this point.

Andres Muñoz underwent Tommy John last March, but a recent setback puts into question how much he’ll be able to contribute this year.

Weather Forecast

For the most part, the weather looks clear this weekend. The only question will come on Sunday where there is rain in the forecast for most of the day. They’ll have to jump through some hoops to make this game up if it’s cancelled since Seattle isn’t out this way very much — and they head to Houston on Monday so they can’t wait around here too long on Sunday — but it may be the only option. We’ll see if the forecast changes.

A big thank you to FanGraphs, and particularly their Roster Resource tool, as well as Baseball Savant for research.