SEATTLE -- Chris Flexen, in so many ways, was among the spearheading pieces behind the Mariners emerging from mediocrity and finally ending their postseason drought. But after a tumultuous 2023 that has been marred by an unsuccessful transition to long relief, the veteran right-hander’s time in Seattle is nearing its end.

Flexen was designated for assignment on Tuesday, a transaction necessary to clear a 26-man roster spot for reliever Trevor Gott, who was activated from the 15-day injured list after missing more than three weeks with lower back muscle spasms.

• Mariners hoping to 'pick it up' for crucial stretch

The Mariners have 10 days to either trade Flexen, have him claimed on waivers -- both of which seem unlikely given his struggles and that he’s earning $8 million this year -- or he’ll be released. Flexen does not have any Minor League options remaining, and given the structure of his contract, he can turn down an outright assignment to Triple-A Tacoma and become a free agent.

“It's probably better for him and for us to go find a spot to start somewhere where he can consistently have a routine where he knows when he's pitching,” Mariners GM Justin Hollander said. “It's a hard thing to do when you've been a starter for most of your life to go pitch out of the 'pen and have the uncertainty and then really know that you're probably pitching in games that are particularly close one way or the other.”

Flexen entered the year on the outside looking in on the rotation after transitioning to the ‘pen last year when the club acquired Luis Castillo at the Trade Deadline. But he was immediately needed back in the rotation after Robbie Ray suffered a left flexor injury that eventually required season-ending surgery. But by that point, after four brutal starts, all losses, Flexen lost his grip on the spot to rookie Bryce Miller.

In 12 relief appearances since, over a span of 45 games, Flexen posted a 6.53 ERA, and opposing hitters had a slash line against him of .326/.383/.558 (.941 OPS).

What went wrong was mostly a lack of command and sound secondary pitches. Flexen’s walk rate soared to a career-worst 9.7%, as did his home run per line drive rate, up from 8.5% in 2022 to 21.6% in '23. With fastball velocity that sat in the low 90s, his secondary stuff became susceptible when he couldn’t locate it. Opposing hitters had a .308 batting average and .431 slugging percentage against non-heaters.

“I think a combination of both,” Mariners manager Scott Servais said. “Flex isn't going to blow you away with a 95 mph fastball and setting up all this other stuff. So he does have to command. You have to be in good counts. And his stuff has changed a little bit since when we first acquired him.”

Having spent all of 2020 pitching for the Doosan Bears in Korea, Flexen was one of the more interesting success stories under the current front office in Seattle. He signed a two-year, $4.75 million contract ahead of the '21 season after being scouted almost exclusively on video. The Mariners, like all teams impacted by the pandemic, did not have a scouting presence overseas that year and were going off what they saw on film.

It worked out masterfully, as Flexen blossomed into the club’s pitcher of the year in 2021 while leading them to a 22-9 record in games he started. Overall, he went 14-6 with a 3.61 ERA in 179 2/3 innings, with 40 walks and 125 strikeouts in 31 starts. He led the team with 15 quality starts.

“Through his own hard work and dedication, he went and remade himself and remade himself into a really good Major League starting pitcher,” Hollander said. “We obviously took a chance on him, and he took a chance on us.”

His 2023 contract vested for $8 million after he accrued a combined 300 innings from 2021-22. Because of that price for a serviceable starter, his production leading into this year and the fact the Mariners had rotation depth in the Minors for the long term, Flexen seemed like a strong candidate to be traded.

But Seattle couldn’t find any takers over the offseason or even into Spring Training. Now the team is on the hook for the remainder that he’s owed, and Flexen will likely be seeking opportunities elsewhere.