Grading the Seattle Mariners' hard-to-swallow 2-1 series defeat vs. Boston Red Sox

The Seattle Mariners came into their three-game set against the Boston Red Sox with momentum after a dominant sweep of the Cleveland Guardians — a much-needed jolt for a team trying to claw its way out of a brutal June slump.

But whatever momentum they had didn’t fully carry over. What followed was a rollercoaster of a series at T-Mobile Park against the Boston Red Sox. In many ways, it mirrored the Mariners’ season to date: Flashes of brilliance, the usual moments of frustration, and enough inconsistency to leave fans fuming.

From dominant starting pitching to another phenomenal Cal Raleigh performance, there were certainly encouraging signs. But once again, Seattle’s offense proved unreliable, and the strategic decisions from the dugout raised a few eyebrows in a pivotal rubber match.

Let’s break down what went right, what didn’t, and how each facet of the team graded out in this latest series against a Rafael Devers-less Red Sox squad.

Mariners vs. Red Sox Breakdown and Grades: Series Results

• Monday, June 16: SEA 0, BOS 2
• Tuesday, June 17: SEA 8, BOS 0
• Wednesday, June 18: SEA 1, BOS 3

Grading the Mariners’ Offense: C

The Mariners didn’t do themselves any favors by opening the series with a lifeless shutout. The opener felt like a flashback to the worst parts of their June slump — nothing doing at the plate, lacking energy, and once again unable to manufacture even a single run. It was undoubtedly a disappointing start.

But credit where it’s due. Seattle bounced back in a big way in Game 2. 

The offense erupted, of course led by none other than Raleigh. “Big Dumper” single-handedly blew the game open with a second-inning grand slam — his 27th home run of the year — and later added a two-run double to bring his RBI total to six on the night. It was one of Raleigh’s most impactful performances of the season and a reminder of how much this lineup leans on him.

Beyond Raleigh, there were other positive signs. The team showed strong plate discipline, working six walks and forcing Red Sox pitchers into stressful counts. Cole Young continued to find his footing at the major league level, notching a multi-hit game and looking increasingly confident. Even Rowdy Tellez swiped a bag in an almost comedic bonus. Yes, if Rowdy Tellez is stealing bases, the baseball gods are most likely smiling down on you.

However, the offense still feels inconsistent overall, Game 2 offered a glimpse of what this group can look like when the right guys are clicking. But that was just one game out of three. The Mariners managed just one more run in the series finale, a sharp drop-off after their explosive showing the night before. Regardless of who’s on the mound, they’ll need to produce more than a single run to stay competitive.

Grading the Mariners’ Defense: A

In true Mariners fashion, the defense once again delivered. Playing crisp, composed, and mostly mistake-free. Even with the constant shuffling of players between the infield and right field, Seattle continues to showcase one of the most fundamentally sound defensive units in baseball.

What’s most encouraging is how this group seems to be gelling more with each passing series. The defensive continuity is improving, even amid all the moving parts. The platoon at first base, firmly established with Donovan Solano and Tellez — has brought some much-needed stability. Both have looked increasingly comfortable, and Solano in particular deserves praise for his glove work. After looking shaky at times early in the season, his glove is heating up alongside his bat. Just watch the highlight reel-worthy snag he made on a scorching ground ball in the series finale — a play he clearly wasn’t making back in April.

Meanwhile, Ben Williamson is still playing polished defense at third, and Young looks more comfortable by the day at second base. It’s no small thing to ask two rookies to hold down critical infield positions, and yet they’re getting it done.

No errors across the series, strong positioning, and solid execution. There’s not much more you can ask for.

Grading the Mariners’ Pitching: A

The Mariners didn’t win the series, but don’t let the final results distract from what was an outstanding showing by their pitching staff — from top to bottom. This group proved why they’re known as the foundation of Seattle’s success.

Let’s start with Logan Gilbert. Making his first start since April 26, Gilbert returned to the mound and looked mostly sharp despite some understandable rust — at least by his standards. He gave the Mariners five solid innings, allowing just three hits and two runs while striking out 10. For most pitchers, that’s a dominant outing — for Gilbert, it just looked like a slightly off day to him.

Bryan Woo followed his start with arguably the performance of the series. The right-hander was flat-out dominant in Game 2, tossing seven shutout innings and silencing a tough Red Sox lineup. He looked in total control from start to finish reminding everyone just how electric his stuff can be when he’s on.

Luis Castillo wrapped the series with a gritty, quality start. He did fall victim to the long ball again — a lingering issue this season. But still managed to limit the damage to three runs across six innings. 

Lastly, there’s the bullpen. Simply phenomenal. Across all three games, Seattle’s relievers didn’t allow a single run. Zero. It was a masterclass in late-game execution, with arms up and down the bullpen contributing to keep Boston quiet once the starters exited. 

All told, this was a clinic by the pitching staff. Between the return of Gilbert, Woo continuing to be the best pitcher in the rotation, the steadiness of Castillo even in a losing effort, and a lights-out bullpen, Seattle proved that their pitching is good enough to win any series.

Grading the Mariners’ Strategy: B

To be clear, Dan Wilson is putting out the best starting lineup he has available — and for the most part, his in-game decisions have aligned with the moment. The batting orders in the first two games of the series made sense, and Seattle's game plan was executed with clarity. But by Game 3, something felt really off.

If there was any signal that the Mariners may have been preemptively punting the rubber match, it might’ve come as early as the bottom of the ninth in the second game of the series. With an 8-0 lead securely in hand, Wilson turned to Andrés Muñoz in what was, by definition, a low-leverage situation.

On one hand, it’s understandable. Muñoz hadn’t pitched since June 9, and getting him some work made sense. But knowing a rubber match loomed the following day, it raised eyebrows. Perhaps he just wanted Muñoz to get back into a rhythm on the mound, especially since he has no qualms using him on back-to-back days — and with an off-day coming up on Thursday, the timing made sense.

Then came Wednesday’s lineup — a patchwork group that all but confirmed the Mariners were prioritizing rest. J.P. Crawford, the lone lefty on the roster with a proven track record against southpaws, was out of the lineup against Red Sox ace Garrett Crochet. Even Miles Mastrobuoni, a better lefty option than Dominic Canzone, got the nod.

It all screamed “maintenance day,” and fans knew the odds of stealing a win with a makeshift lineup weren’t great. Giving Dylan Moore the start made sense, but something about the lineup just didn’t feel right. And it wasn’t. Crochet carved, the offense sputtered, and the Mariners managed just one run in a game that never felt particularly competitive.

Yes, baseball is a marathon, and with a 10-game road trip and 17 straight games ahead, giving players a breather is justifiable. Still, it’s hard to shake the feeling that this was a missed opportunity. After stumbling through most of the month, this stretch of the schedule should still be considered critical for regaining momentum. The Mariners don’t have the luxury of coasting right now, not with a Wild Card race that will again more than likely be decided by the slimmest of margins.

If Seattle ends up falling just one or two games shy of a postseason berth, don’t be surprised if fans look back on this stretch — and maybe even this series — as one that slipped away.

The Mariners have a massive road test against the NL Central-leading Chicago Cubs at Wrigley Field starting this Friday. Let’s hope those rest days pay off, because the margin for error continues to shrink from here on out.