Mariners May Have Found Their Most Useful Bullpen Fix In Overlooked Cooper Criswell

One clean eighth inning may have opened a much bigger door.

Apr 12, 2026; Seattle, Washington, USA; Seattle Mariners relief pitcher Cooper Criswell (88) reacts to defeating the Houston Astros at T-Mobile Park. Mandatory Credit: Steven Bisig-Imagn Images | Steven Bisig-Imagn Images

Cooper Criswell didn’t arrive in Seattle as the kind of pitcher fans were circling on the roster and dreaming up late-inning scenarios around. He came in as depth. A swingman who could lengthen out in spring training, compete for a back-end rotation spot while Bryce Miller worked his way through injury trouble, and then settle into whatever role was left once the roster took shape. Every team needs pitchers like that, even if nobody is buying jerseys because of them.

But the Mariners may have stumbled into something a little more interesting than a basic depth piece. Criswell’s first real high-leverage test with Seattle came Wednesday against The Athletics, and it looked almost suspiciously easy. With the Mariners holding a one-run lead in the eighth inning, Dan Wilson turned to Criswell to protect the bridge to Andrés Muñoz. Criswell needed only nine pitches to retire the side and record the first hold of his six-year major league career, according to MLB.com’s Josh Kirshenbaum.

This was not the role Seattle originally seemed to have in mind for him. Criswell’s first seven appearances with the Mariners came in lower-leverage spots, either with Seattle trailing or comfortably ahead. Before Wednesday, he had mostly been operating as the kind of arm managers use to keep a game from getting out of hand or save the bullpen from getting torched too early.

Then the Mariners needed real outs, and Criswell gave them exactly that.

Mariners Are Getting Unexpected Bullpen Value From Cooper Criswell

The broader numbers make the early fit even more intriguing. Criswell entered April 23 with a career 4.29 ERA, 1.41 WHIP, 122 strikeouts and 165 2/3 innings across 53 major league games. It’s the résumé of a pitcher who has bounced around, started, relieved, survived roster crunches, and learned how to stay useful.

With Seattle this year, though, the production has been sharper. Through eight games, Criswell owns a 1.64 ERA with one save and nine strikeouts over 11 innings. Again, we are not talking about a massive sample. But for a Mariners bullpen that has already had to do some April problem-solving, small signs can become meaningful pretty quickly.

Wilson said after the outing that Criswell has shown he can take the ball in different situations, whether that means length or getting the eighth inning to Muñoz. That’s the exact kind of pitcher managers love because it keeps the rest of the bullpen from becoming too rigid. Criswell can cover multiple innings if a starter exits early. He can absorb lower-leverage work when the game tilts the wrong way. And now, apparently, he can be trusted when the Mariners need three clean outs before handing the ball to their best reliever.

The Mariners have already seen how quickly bullpen plans can get messy. Carlos Vargas landed on the injured list before making his season debut. Casey Legumina got a tough eighth-inning assignment earlier in the week, gave up three runs, and was designated for assignment the next day. Matt Brash has not been locked strictly into the eighth inning lately, and the staff is also trying to manage early-season back-to-backs. That leaves Seattle needing more than a traditional pecking order. It needs pitchers who can bend without breaking.

The big-name bullpen answer is always more fun. Fans want the guy throwing 99 with a wipeout slider and a nickname by Memorial Day. Criswell is more subtle than that. He doesn’t scream late-inning weapon. He just throws strikes, changes looks, keeps the ball moving, and makes the game feel a little less chaotic. For this team, that has value.