WASHINGTON D.C. -- Seattle Mariners closer Andres Munoz left Sunday's 10-1 loss against the Washington Nationals in the bottom of the eighth inning with "lower back tightness."

Manager Dan Wilson called him day-to-day, and Munoz himself indicated afterwards that the issue was nothing to worry about.

That said, I'm going to worry about this issue - at least a little bit.

Let's dig a little deeper.

In fairness, Munoz has dealt with back issues before and has always come out the other side. He missed a week's worth of action for a lower back issue in 2024 and reportedly pitched for much of that season with a problematic lower back.

While you never like to have a repetitive issue to manage, Munoz has managed it, so we should all have faith that he's going to be able to manage it again.

That said...

After losing Matt Brash for "a while" because of a right lat strain, the Mariners bullpen is thin on leverage arms. They can ill-afford Munoz to be injured - or compromised - as they try to hold onto a tenuous 0.5-game lead in the American League West. As a result of the six-man rotation, the bullpen is also thin on numbers in general, so it can't afford to have Munoz down there, but not able to pitch on any given day.

Munoz hadn't pitched for six days heading into Sunday's appearance. He had pitched on Monday, June 8 and then again on June 14. Shouldn't six days off help clear up any issues? This isn't an overuse injury.

Is there a chance it's an underuse injury? That Munoz stiffened up because of lack of work? I guess either are possible, but without definitive answers, it's problematic.

Munoz has struggled this season, going 3-4 with a 5.92 ERA. His velocity and strikeout numbers are through the roof, but he's been hit much harder this year than in either of his previous two All-Star campaigns. 

Has his back been a lingering issue that helps explain some of those struggles? Have his mechanics suffered as a result of this? Has this back issue led to a lack of confidence on the mound?

We really don't know, but it's all possible, which again, makes the situation troublesome for the Mariners moving forward.

The Mariners will play the Baltimore Orioles on Tuesday at 6:40 p.m. PT. Logan Gilbert will start against Brandon Young.

The latest episode of the 'Refuse to Lose Territory' podcast, featuring interviews and footage from the M's last series against the Washington Nationals is out now. You can listen here, or you can watch on YouTube below.

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