As the Seattle Mariners return home on Friday night (6:45 p.m. PT) to take on the Kansas City Royals, all eyes are on Matt Brash.

The reliever left Wednesday's game against the Minnesota Twins with "right side discomfort," and while no official update has been given yet, there's a fair amount of worry that Brash will have to miss some time.

Neither Brash nor manager Dan Wilson seemed overly concerned after the game on Wednesday, but that doesn't really mean much until we learn the result of Thursday's imaging.

As I said on the most recent 'Refuse to Lose,' podcast, Brash is an irreplaceable part of the Mariners bullpen. And that's true whether he's out for one day, 10 days or six weeks. It doesn't matter.

Brash is the owner of a 0.00 ERA through 14 outings and possesses the kind of swing-and-miss stuff that bullpens salivate over.

If he's not there, not only do the Mariners miss out on their eighth-inning and shut down reliever, but it also puts the rest of the bullpen in a bind.

From the podcast: 

"If Matt Brash is not here, what does that mean? Well, it means that Bazardo, Ferrer, Speier all probably have to throw an inning later than they're used to. Now Bazardo and Speier become your 8th-inning guys instead of Brash. What does that mean?

That means that somebody else has to clean up the fifth or clean up the sixth, and we've talked about the pivot guys in the bullpen struggling through the early part of the season. Well, they're about to get more action as well if Matt Brash is out. Then you're going to have have more pressure on the starters to go a full six or seven to avoid needing those pivot guys en masse.

You also are going to have a situation where I mean, look, with five leverage guys, you can give a couple of guys a day off here and use two or three leverage guys there, and then the next day, those guys can be off, and the guys that were off can come back and pitch. If you shrink the leverage guys, you are ending up in a spot where you're going to have more guys needed to throw back-to-back, which has a toll at the end of the season. Matt Brash is an irreplaceable loss for the Mariners."

A four-year veteran, Brash is 16-11 in his career with a 3.10 ERA. He's become one of the best set-up men in the American League.

The M's are 16-16 and in second place in the American League West while the Royals are 12-19 and in last place in the American League Central.

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