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Seattle Mariners reliever throws during a game against the Washington Nationals on May 29 at T-Mobile Park. Steven Bisig-Imagn Images

Matt Brash's Slider Draws Extremely High Praise From Seattle Mariners Manager

Originally posted on Seattle Mariners on SI
By Teren Kowatsch | Last updated Jul 9, 2025 9:45 AM ET

Seattle Mariners reliever Matt Brash has been one of the best bullpen arms in the game since returning from injury at the beginning of May.

Brash missed all of 2024 while recovering from Tommy John surgery, which was a big blow to the M's bullpen as they missed the playoffs by one game. He led the team, and the majors, in appearances with 78 in 2023. His original timeline had him returning around the All-Star Break this season.

Brash returned ahead of schedule and made his season debut May 3. The fact he beat the initial expectation for his return by two months was impressive by itself. What's even more impressive is that Brash has immediately picked up where he left off.

Entering Wednesday, Brash has posted a 0.47 ERA with 20 strikeouts in 19.1 innings pitched across 21 appearances. He has one save in as many opportunities, with four holds. He's allowing an opposing batting average of .191 to go with a 1.03 WHIP, which would both be single-season career highs if the year ended today.

"It is great to have Matty back," Seattle manager Dan Wilson said before a game against the New York Yankees on Tuesday. "Obviously such a big piece to our bullpen. Getting him back at the time we did was a big lift. He's one of your big back-end guys. ... Seemed like he hasn't missed beat, which is pretty amazing given he missed a lot of time."

Part of the reason for Brash's immediate resurgence for the Mariners bullpen has been his slider — which has an argument as one of the most effective pitches in baseball. Brash has thrown the slider 200 times this year, more than any other offering in his repertoire by a wide margin. His second most-used pitch is his sinker/two-seam fastball, which he's thrown 79 times, according to Baseball Savant.

Brash's slider is a deadly weapon against any batter. He's thrown it 94 times against right-handed hitters and 106 times against lefties. Brash has struck out 14 batters with the slider and is allowing an average of just .158 against it. He's generated a whiff rate of 32.1% with the slider and a put-away rate of 26.4%.

Matt Brash, Ridiculous 85mph Back Foot Slider.

20 inches of horizontal break. pic.twitter.com/J1j9pvySTJ
— Rob Friedman (@PitchingNinja) June 28, 2025

Wilson highlighted the slider in his pregame interview and compared Brash's elite offering to that of two of the skipper's former teammates, who are both World Series champions.

"That slider is one of the best, if not the best in the big leagues, and it's a really tough pitch. He has thrown it very well and he's thrown it in some high-leverage situations and has really thrown the ball well for us. ... Kind of a mixture of (Jeff Nelson and Randy Johnson's). But it's a nasty pitch, and he's been real consistent since coming back, too, and he's been great for our bullpen."

Nelson pitched for Seattle from 1992-95, 2001-03 and '05 and made the All-Star Game in 2001.

Johnson, a National Baseball Hall of Famer, played for the Mariners from 1989-98, earned five of 10 career All-Star nods with the franchise and he won the first of five career Cy Young awards in 1995.

Wilson, who played for Seattle from 1994-2005, was the main catcher for both pitchers while they were with the M's and saw first hand how deadly their respective sliders were.

It's high praise for Brash, who's been almost flawless this season as the set-up man for All-Star closer Andres Munoz. If both Brash and Munoz continue at their current pace, they'll have an argument for the best high-leverage reliever duo in the American League this season.

This article first appeared on Seattle Mariners on SI and was syndicated with permission.

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