It’s been a while since the Houston Astros took the AL West lead away from the Seattle Mariners, and they’ve put some space between them and the M’s in the time since.

Entering play Tuesday, the Astros are 50-34, six full games ahead of the Mariners for first in the division. Seattle remains in position for the AL’s third wild card.

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The idea that the Astros lead the AL West isn’t surprising considering they’ve won seven of the last eight division crowns, but it is surprising considering a couple things that have not been going the way they’ve wanted this season.

First, injuries have been a big issue. All-Star slugger Yordan Alvarez had a setback Tuesday with a hand fracture, and breakout shortstop Jeremy Peña joined him this week on the injured list.

Second, the Astros have not been a great offensive team this year. They rank 22nd in MLB with 350 runs scored, whereas the Mariners are 12th with 386. They’re 14th in on-base percentage at .320 (Mariners are sixth at .325). And they’re 15th in OPS at .719 (Mariners are 10th at .729).

“Their best hitter (Alvarez) has been on the IL for two months with a fracture that the team didn’t diagnose for a month,” The Athletic’s Chandler Rome, who covers the Astros, told Seattle Sports’ Bump and Stacy on Tuesday. “Their next best hitter (Peña) just went on the IL with a fracture that it took the team four days to find. And somehow they just keep rolling along.”

The reason for that: pitching and defense.

Houston is fifth in MLB with a 3.47 ERA, second in opponent average at .220, and first in WHIP at 1.15. Leading the way have been starters Hunter Brown (1.74 ERA, 0.89 WHIP) and Framber Valdez (2.72 ERA, 1.13 WHIP), and relievers Bryan Abreu (1.63 ERA, 1.11 WHIP) and Josh Hader (1.67 ERA, 0.69 WHIP).

“The theme of it is they’re pitching incredibly well,” Rome said. “… When you look at it, they have two of the best starting pitchers in baseball in Hunter Brown and Framber Valdez. They have two of the best relievers in baseball in Bryan Abreu and Josh Hader. When you send out Brown and Valdez twice every five days, you have a very good chance to win. And when you get late in a game with a one- or a two-run lead, you have a very good chance to win with Bryan Abreu and Josh Hader going out there.”

That plus a stingy defense particularly in the infield, Rome said, has translated into a lot of success in close or low-scoring games.

“The Astros have already won 18 one-run games this year. They won 17 all of last season,” he said. “They’ve won 19 games this year when they’ve scored three or fewer runs. They won 12 of those games all last season. So they are a run-prevention machine.

“They have the best defense in the American League, they have the best defensive infield in the American League. So to put it plainly, they pitch it really well, and when someone does make contact off their pitchers, they’re usually going to catch it. And that’s a good recipe to win a bunch of close games like they have.”

Houston’s bats aren’t that big

Even with Houston’s pitching and defense, the offense leaves hope alive in Seattle that the Astros could be vulnerable down the stretch. That’s especially so considering the M’s lineup has been better in 2025 and their pitching appears to be turning a corner after an uncharacteristic first few months.

Rome pointed to Jose Altuve (.737 OPS), Yanier Diaz (.660) and 2025 addition Christian Walker (.635) as sore spots for the Astros this year, especially with Alvarez having played just 29 games. Walker stands out the most, as he joins José Abreu as high-paid signings at first base in recent years by Houston that struggled right away.

“They currently have $38 million sunk into first base, where they are getting absolutely nothing,” Rome said. “Christian Walker is one of the worst everyday players in baseball, and they keep running him out there every day – A, because they can because they have a 6 1/2 game lead in the division, and B, because they have no other options.”

So yes, the Astros have a decent lead in the division now. But they have a clear need to address that otherwise could be their Achilles heel.

“They’re gonna have to find a way to produce more runs,” Rome said. “… They need Jose Altuve to not necessarily be 2017-2019 Jose Altuve, but be a little bit better, maybe closer to his career norms. And then anything they can get from Christian Walker and Yainer Diaz would be welcome, because those two guys have have been the biggest disappointments on the team.

“It’s hard to look at their lack of run production and not point to Christian Walker and Yainer Diaz, two guys that they thought coming into spring training would hit in the middle of their order all season. Christian Walker hit seventh the other day, Yainer Diaz hit eighth. It has not been a good season for the middle of their order and they need to get that fixed in a heartbeat because look, they can pitch it and they can prevent runs as well as anybody, but at some point you do have to score runs to win some games. And this team does have trouble scoring runs.”

Hear the full Bump and Stacy conversation with The Athletic’s Chandler Rome in the podcast at this link or in the player near the top of this post. Catch Bump and Stacy from 10 a.m. to 2 p.m. weekdays on Seattle Sports.

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