Mariners designate Casey Legumina for assignment, call up Alex Hoppe from Tacoma

One bullpen arm’s on the way out. One fresh arm’s in.

The Mariners designated right-hander Casey Legumina for assignment on Tuesday, a day after he was tagged for three eighth-inning runs in a rare high-leverage appearance during a 6-4 loss to the Athletics.

Legumina, a Gonzaga product, had a 5.43 ERA in 56 appearances for the Mariners since the start of the 2025 season. Legumina was out of minor-league options, meaning he had to be DFA’d to clear room on the 40-man roster.

Alex Hoppe, a 27-year-old right-hander with a big fastball, was promoted from Triple-A Tacoma to take Legumina’s place.

Hoppe had not allowed an earned run in eight appearances for the Rainiers this season, with just four hits allowed and a 12-to-3 strikeout-to-walk ratio in eight innings.

He leads the Pacific Coast League with four saves, and he threw a rare immaculate inning — three strikeouts on nine pitches in one inning — on April 7 at Sugar Land. 

His first appearance for the Mariners will be his MLB debut.

“It’s a call you kind of dream of ever since you’re a little kid,” Hoppe said Tuesday afternoon inside the home dugout at T-Mobile Park.

On Monday, Hoppe traveled with the Rainiers to Oklahoma ahead of their series against the Oklahoma City Comets.

Around midnight, he got the call from the Mariners that he was being called up to the big leagues for the first time. After calling family and friends to alert them of the news, he managed to sneak in a few hours of sleep before catching an early-morning flight back to Seattle, with a short layover in Denver.

“It’s pure excitement,” he said. “Obviously anxiousness and nerves, because you’re in the big leagues; you’re part of a small select group of individuals that (has) done this throughout history.”

He arrived at T-Mobile Park around 2 o’clock Tuesday and got a quick tour of the clubhouse and the field.

“I’ve never been in a stadium with stands this high,” he said.

The Mariners acquired Hoppe in a November trade with Boston, sending to the Red Sox minor-league catcher Luke Heyman (Seattle’s 14th-round draft pick last summer).

Hoppe was asked what his main impressions were from his first spring training in the Mariners organization.

“I would say the positivity and the belief they have in me,” he said. “They have told me from Day 1: ‘Hey, you’re gonna help us win games in the big leagues.’ …

“They believe that probably more some days than I believe in myself, which is spectacular to hear from an organizational standpoint.”

Hoppe had a fastball that reportedly touched 100 mph but carried a reputation as a pitcher who struggled to throw consistent strikes. He had finished last season at Triple-A Worcester, where he posted a 4.76 ERA in 45.1 innings with a 27.6% strikeout rate and 11.8% walk rate.

He had a 13.7% walk rate at Double-A earlier in the year, a figure far too high for the Mariners and their Dominate The Zone pitching ethos.

The directive, then, from Mariners coaches and analysts over the offseason was obvious.

“It’s pretty much like just being in the (strike) zone,” Hoppe said. “My stuff’s good enough to play at this level. We’ve known that. But how consistent can I be in that box? It’s me versus the box in there. It’s like, how many times can I put that circular ball in that box? And if I do that more times than not, I’m more than likely going to have great success.”

Hoppe has thrown a four-seam fastball (97.6 mph), a slider (88.6), a cutter (90.7) and an occasional changeup (93.3) in Tacoma, holding hitters to a .148 batting average to start the season.

Notes

— Mariners top prospect Colt Emerson was out of the Tacoma lineup Tuesday as he nurses a sore wrist. He was also out of the lineup Sunday, giving him three days off in a row to rest (Monday is a scheduled off day throughout the minor leagues).

— The Mariners lost RHP Blas Castaño to the Colorado Rockies on Tuesday after he was claimed off waivers. The Mariners had DFA’d Castaño last week. Castaño made one relief appearance for the Mariners last season, spending most of the past two seasons in Triple-A.