With spring training camps opening up this week, there's already a major development in the American League West race.

As noted by Buster Olney of ESPN, the Houston Astros, the chief rival of the Seattle Mariners, are monitoring the progress of closer Josh Hader's shoulder.

As spring training begins for the Astros, All-Star closer Josh Hader has been throwing lightly and on flat ground. He and the Astros hope to learn more about where he stands in his prep for the season in the middle of this week.

Hader missed the last month and a half of the season in 2025, not appearing in a game after Aug. 8. The notion that he's still not 100 percent after six months is troubling for Houston, and a potential major factor for the Mariners in the division.

The Mariners won the American League West in 2025, going 90-72 before advancing to the American League Championship Series. It's no secret that the Astros dealt with injuries throughout the 2025 campaign, and if they are already dealing with them again in 2026, that's a big development for the M's. Nobody wants to be handed anything because of another team's health problems, but it's a reality of the game, and a benefit to the Mariners when the Astros aren't 100 percent.

Now 31 years old, he's been one of the top relievers in the game for years. He went 6-2 in 2025 with a 2.05 ERA, appearing in 48 games. He struck out 76 batters in 52.2 innings, also registering 28 saves.

A nine-year veteran of the Milwaukee Brewers, San Diego Padres and Astros, he's 34-31 lifetime with a 2.64 ERA. He has 829 strikeouts in 512.1 career innings because of his upper-90s fastball and wipeout slider.

He is a six-time All-Star and his presence completely solidifies the Astros back-end of the bullpen. If he's not ready to start the season, the 'Stros will likely turn to Bryan Abreu. Him falling out of a traditional leverage role also impacts the rest of the Houston bullpen.

The M's will host the Astros for four big games in April, April 10-13, which could certainly be important as the two teams come down the stretch in September. If Hader is unable to play, the advantage swings to the M's in those matchups.

It's absolutely a storyline to monitor moving forward.

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