Seattle Mariners vs. Toronto Blue Jays: ALCS Preview

After some dramatic ALDS matchups, the stage is set for the series to determine the AL's representative in the World Series.

SEATTLE, WA - MAY 10: Vladimir Guerrero Jr. #27 of the Toronto Blue Jays pats Julio Rodriguez #44 of the Seattle Mariners on the back at first base during a game at T-Mobile Park on May 10, 2025 in Seattle, Washington. The Blue Jays own 6-3. (Photo by Stephen Brashear/Getty Images)

With the American League whittled down to its final two teams, the AL Championship Series is finally upon us.

The top two seeds in the American League this season, the Toronto Blue Jays (AL East Champions) and the Seattle Mariners (AL West Champions), are pitted against each other in what should be a battle of fierce rivals and a rematch of the 2022 AL Wild Card Series played in Toronto.

The Mariners will play their first game in the ALCS since they last won an AL West title in 2001, the year they set the single-season wins record with 116 victories. The Blue Jays visit the ALCS for the first time since doing so in consecutive seasons in 2015-16. For both franchises, a trip to the World Series would be historic, and this series should encompass all the built-up passion of their fanbases and players.

Toronto may have won the season series against Seattle by winning four out of six (including a sweep in Seattle), but here’s how both teams stacked up league-wide in the regular season:

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HITTING:BLUE JAYSMARINERS
HR191 (T-11th)238 (3rd)
RBI771 (T-3rd)734 (10th)
AVG.265 (1st).244 (20th)
OBP.333 (1st).320 (T-10th)
SLG.427 (T-7th).420 (10th)
OPS.761 (3rd).740 (10th)
wRC+112 (T-4th)113 (T-2nd)
fWAR32.6 (2nd)26.5 (9th)
PITCHING:
ERA4.19 (19th)3.87 (13th)
FIP4.26 (22nd)3.97 (9th)
K%23.5% (8th)23.2% (T-9th)
BB%8.5% (T-16th)7.4% (3rd)
fWAR11.7 (21st)14.2 (18th)

Rested vs. Exhausted

The Blue Jays and Mariners are entering the ALCS with completely different levels of tiredness.

The Blue Jays clinched their ticket by defeating the New York Yankees on Wednesday. The Mariners are coming off a five-game set against the Detroit Tigers, the final game of which lasted fifteen innings, and Seattle utilized three starting pitchers in an effort to advance.

Toronto had the time to completely reset its starting rotation after the ALDS, with Kevin Gausman to pitch the first game, Trey Yesavage the second, and Bieber the third. The fourth game could be a bullpen game again, though Max Scherzer or Chris Bassitt will likely get the start.

Seattle will be without three starting pitchers early in the ALCS due to the sheer length of ALDS Game 5, those being George Kirby (ALDS G1 & G5 starter), Luis Castillo (G2 starter, relief in G5), and Logan Gilbert (G3 starter, relief in G5). The Mariners will now have to start Bryce Miller in G1 of the Championship Series, while the Blue Jays will have their rotation lined up exactly how they’d like.

Keys to Victory: Seattle Mariners

Mariners Are Due for an Offensive Breakout

Scoring more than three runs only once in the ALDS against Detroit, Seattle needs to get its offense back into the driver’s seat against the Blue Jays, whose offense has shown itself to be among the league’s best all year long.

The Blue Jays reached the five-run threshold in every game of their matchup against the Yankees, which was a mark that granted them a 71-4 record in the regular season when they reached it. Seattle will need to keep up with Toronto’s bats by bringing the heat offensively themselves.

60 home run-hitter Cal Raleigh was a weapon at the plate in the LADS, and he really spearheaded this Mariners offense like he did in the regular season. He slashed .381/.480/.571 and led both teams in the series with eight hits and four walks (tied with Victor Robles). He also led Seattle with a 1.051 OPS, and was second in the series in hitter WPA (0.34) behind Kerry Carpenter (0.38).

Julio Rodríguez, however, was rather quiet this past series, batting just .174 with a .588 OPS, and the majority of Seattle’s other hitters also had an underwhelming series and an OPS under .600. So, their bats will need to bust out of this funk against the Blue Jays.

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Location, Location, Location

Something to always consider when the Blue Jays visit Seattle in the regular season is the large presence of West Coast Blue Jays fans who show up in droves (and at times outnumber Mariners fans!) at T-Mobile Park.

Toronto’s home games in the ALDS proved to be very rowdy at times and made the Rogers Centre a difficult place for the Yankees to gain momentum in. If Toronto fans are able to give the games at T-Mobile Park any less of a home-game feel for Seattle, this might play a crucial role in the series.

Games 1, 2, 6, and 7 will be in Toronto, while Games 3, 4, and 5 are scheduled to take place in Seattle. So, the Mariners will need to take a strong hold of the momentum in the middle of the series while they’re playing at home. The Blue Jays swept Seattle in their series at T-Mobile Park earlier this season, outscoring the Mariners 21-7 in those three games, so they’ve proven their ability to hit in what is a pitcher’s park in Seattle.

The M’s need to establish their ability to dominate the Blue Jays at home and not get run out of the Rogers Centre like the Yankees. It’s going to be a tough ask for the Mariners, but their fans are dedicated enough that they’ll make it hard on the Jays when the series makes its way out west.

Rotation Reliability

The Mariners have had one of the league’s most reliable starting rotations for several years now, and they’ll need them to show out in this series. Only once in the ALDS did a Mariners starter record a quality start (Gilbert, G3), but their 67 quality starts in the regular season ranked seventh in MLB.

The Tigers were able to get Kirby, Castillo, and Miller out of their respective starts within five innings. Seattle’s bullpen was very capable of keeping the team in games, but how long can the Mariners rely on their bullpen to bail out their rotation? With three of their top starters appearing in the final game of the ALDS, their bullpen will have to be strong against Toronto.

The Mariners’ bullpen had a 4.33 ERA in the ALDS. Meanwhile, Toronto’s pen had a 6.30 ERA in their ALDS matchup, although the Jays were able to muster an incredible nine-inning bullpen game in which they only surrendered two runs in their final game of the series. Seattle’s relievers were similarly impressive in their ability to continuously stave off the Tigers’ offense in Game 5, albeit with several innings from their starting pitchers as well.

Keys to Victory: Toronto Blue Jays

Yesavage’s Dominance

Yesavage had an incredible postseason debut in Game 2 against the New York Yankees, tossing 5.1 innings of no-hit baseball and only allowing two baserunners (walk, error) while striking out eleven. He was able to shut down a very strong New York lineup and hardly allowed any contact thanks to a near-70% whiff rate on his dominant splitter.

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He’s likely to get Game 2 of the ALCS in Toronto like he did in the ALDS, and the Mariners, like the majority of the league, have not seen Yesavage in a game yet. It could alternatively be Toronto’s plan to allow Bieber to start a game at home to get some of his confidence back after a rough 2.2-inning outing in the Bronx.

Regardless of what park Yesavage pitches in next, his performance thus far in the playoffs has lived up to his quote about pitching amid playoff intensity: “I’m built for this.”

Ridiculous Offense

The biggest story of Toronto’s first-round matchup was their relentless offense and consistent ability to put the ball in play. They boasted the league’s best strikeout rate at the plate (17.8%) and were able to limit the Yankees’ starting pitchers to two or fewer strikeouts in each game of the series.

Despite Seattle’s dominant starting rotation, the M’s are going to be put through the wringer by Toronto’s insane contact ability.

The Blue Jays got three-plus hits from eight different hitters in the ALDS and only had five hitters record more than one strikeout at the plate. They led MLB in batting average and on-base percentage in the regular season, and their offensive ability has been responsible for them taking over games throughout the year and into the playoffs.

Toronto’s pitching wasn’t especially dominant game-in and game-out, so their offense had to pick the pitchers up, and it did plenty of that. The Blue Jays have the talent to work the life out of a pitching staff, and they put that on full display against the Yankees. It’ll be interesting to see how Seattle will handle the top-to-bottom display of dominance that is the Blue Jays’ offense.

Prediction

Blue Jays in 6

I think this series will end in Toronto no matter what. You could reasonably put your money on either team, but it’s more likely than not that the Blue Jays come out on top.

This is not to disparage the Mariners at all, but rather a prediction that the Blue Jays will continue to be as dominant as they were in the ALDS. If they’re able to stay as locked in on all sides of the ball as they were against the Yankees, the Mariners won’t have much of a chance.

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That being said, predicting the Blue Jays to win in six games indicates a strong amount of fight from the Mariners. This will not be an easy series for either team. This is going to be an incredibly close ALCS matchup and should see both teams pushed to their limits.

The Mariners are coming off a tough-fought series in which they barely edged out Tarik Skubal and the Tigers. It’s going to take a lot for them to come out on top over the Blue Jays in this series.

Regardless of who wins, the American League will send one of these teams to the World Series in historic fashion: the Mariners for the first time in their franchise’s storied history, or the Blue Jays for the first time since their historic back-to-back wins in 1992 and 1993.

No matter how this series goes, it’s going to be an absolute treat for fans of any team to watch, although more stressful for those of the teams involved. The Blue Jays have the upper hand on paper, but anything can happen.