3 reasons the Seattle Mariners’ lead in AL West is almost gone

The Seattle Mariners lead the AL West.

That’s something we’ve gotten quite used to saying over the first two months of this MLB season. But the way things are going, we might need to get out of the habit soon.

Cal Raleigh details the key improvement he made at the plate

The M’s had a comfortable lead of 3 1/2 games over the second-place Houston Astros just over a week ago. Entering play Friday, however, that lead has shrunk to just a half-game, with the Mariners sitting at 30-25 after a series loss at home to the Washington Nationals (26-30), and the Astros at 30-26 after back-to-back series wins over the M’s and A’s.

Having flashbacks to last year, where the Mariners coughed up a 10-game lead in the division to Houston all before the end of July? Understandable.

So what’s going on with Seattle? Let’s look at three problems that have held the Mariners back while they’ve gone 12-13 in the month of May.

Three things that have hurt the Mariners in May

1. They’re not scoring runs like they were.

The reason the Mariners were in first place in the… first place was their improved offense in April. Entering May 1, the Mariners were third in the American League and eighth in MLB in total runs scored, averaging 5.07 runs per game. Only the Dodgers and Yankees had more home runs than the Mariners’ 45, only the Yankees and Cubs had better team on-base percentages than the Mariners’ .339, and no other team had a better walk percentage (11.5%) than the M’s.

In May, the Mariners rank 10th in the AL and 20th in MLB in total runs, averaging just 3.27 runs per game – a drop-off of 1.8 runs per game from the first month of the season. Seattle’s down to ninth in the AL and 13th in MLB in home runs this month with 28 in 25 games. The Mariners’ on-base percentage for May is .305, which is 11th in the AL and 24th in MLB. And their walk rate is just 8.3% (sixth AL, 16th MLB).

In terms of individual players, the big differences between April and May are the hitters in the second tier of Seattle’s lineup. Most specifically Jorge Polanco, who is no longer red-hot, and Randy Arozarena, who has had a power outage this month.

Polanco slashed .384/.418/.808 for a 1.226 OPS with nine home runs and 25 RBIs in 22 games through April – and the switch-hitter did that hitting almost exclusively left-handed and serving as Seattle’s DH due to an oblique issue. Polanco has started playing sparingly in the field and against left-handed pitchers this month, but his numbers at the plate have tanked: .136/.208/.212 slash for a .420 OPS with just one homer and five RBIs in 21 games in May. And entering Friday, he’s hitless in his last seven games.

As for Arozarena, he hit just .208 over his first 29 games of the season, but he had five homers to keep his slugging (.406) mark up, and he drew 21 walks to give him a strong .359 on-base percentage. Together, it added up to a .764 OPS going into May. But in 24 games this month, he has just one homer and has walked only eight times. So while his average is up, the rest of his slash line is down: .233/.340/.349 for a .689 OPS.

2. T-Mobile Park hasn’t been Home Sweet Home.

This one is pretty straightforward.

The Mariners are 16-12 in road games this year, and just 14-13 at home. But if we focus solely on May, Seattle is just 2-7 at T-Mobile Park.

So much for a home-field advantage.

This is where Seattle’s two other problems during their May swoon connect.

The offense kept the Mariners not just afloat but thriving in April. But in May, they have 28 runs in their nine games at home for an average of just 3.1 runs per game. Making matters worse, nine of those runs came in a win over Washington on Monday. So take that game out of the equation, and Seattle is averaging just 2.38 runs in the remaining games. That… is not good.

When we factor in the pitching, which we’ll do in the next section, things get even uglier.

3. This hasn’t been “the Mariners’ starting rotation.”

The Mariners are built around their pitching staff, especially the starting rotation. But they’ve been down three of their five top starters at various points this season due to arm issues, and even though Emerson Hancock and Logan Evans have mostly done well when they’ve been up from Triple-A Tacoma, the rotation has been uneven.

Especially at home.

Seattle’s rotation is built for success at T-Mobile Park, which is legitimately the toughest MLB ballpark to create offense in. This month, that last part has certainly been true for the Mariners’ lineup. But it hasn’t been for their competition.

In the nine games at T-Mobile Park this month, opposing teams have scored 55 runs for an average of 6.11 runs per game. That certainly does not make for a great combination with Seattle’s offensive woes at home.

On the year, Seattle is eighth in the AL and 15th in MLB with a 3.83 ERA, and ninth in the AL and 19th in MLB with a 1.32 WHIP. Neither the rotation (3.97 ERA, 1.29 WHIP) nor the bullpen (3.62 ERA, 1.37 WHIP) is having a great season, even if starter Bryan Woo (5-2 record, 2.69 ERA, 0.94 WHIP) and closer Andrés Muñoz (17 saves, 0.00 ERA, 0.68 WHIP) are both pitching like All-Stars.

You would think this is where the Mariners can get back on track, at least. Sure, George Kirby’s first two starts since coming off the injured list were rough, and Bryce Miller struggled before a short IL stint of his own. But their track records suggest they’ll be much better than they have been so far. And then you have opening day starter and 2024 All-Star Logan Gilbert coming back in a matter of weeks, and he was off to a great start (3-1, 2.83 ERA, 1.26 WHIP) before an elbow flexor bundle strain sidelined him in late April.

So that’s why the Mariners’ lead in the AL West is no longer comfortable. But it also shows the path to the postseason for Seattle. A lot of things have gone wrong for the M’s this year, and they’re still in first place – for now. You know the hitters have shown it can be better than it has been this month. You know the starting rotation hasn’t been itself yet in 2025.

There’s still two-thirds of the season to go. The trade deadline will provide opportunity for improvement. The Mariners have shown they have the pieces to the puzzle. There’s still plenty of time for them to put it all together.

More on the Seattle Mariners

• How Logan Gilbert fared in first rehab start in minors
• Bryce Miller’s return to the Mariners’ rotation set for Saturday
• After 5 DFA’s, Mariners pitcher is in the majors again
• Jon Morosi hopes MVP voters will see Cal Raleigh’s value
• Seattle Mariners debut coming soon? Cole Young records 5-hit game

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