SEATTLE — Over the past decade, the Seattle Mariners have built one of baseball's most successful pitching enterprises by drafting young arms, developing them through their minor league system and molding them into viable major league pitchers.

If not an exact blueprint, the Mariners at least have a dog-eared operating manual on best practices for young pitchers.

Their latest project — and the most fascinating pitcher the Mariners have ever had in their system — doesn't fit quite so neatly into any model.

There is no manual for what to do with 21-year-old Jurrangelo Cijntje, their Dutch-born Curaçao native who has all the promise of a future major league pitcher — while throwing with both arms.

"Everything is still very much a test study," Jerry Dipoto, the Mariners' president of baseball operations, said. "The way he does it, and at the velocities he does it, and with the kind of ceiling he has — no one's ever done it."

All of which has led to some interesting conversations around the Mariners' short-term and long-term plans for Cijntje, a 2024 first-round draft pick who is navigating his first foray into pro ball with the High-A Everett AquaSox.

The Mariners' strategy for their ambidextrous pitcher is both ambitious and ambiguous.

"I wish I could stamp: 'This is his routine,' " Dipoto said. "We're learning as we go. You can't just pull out the book and go, 'This is what we're doing with the switch-throwing starting pitcher who throws in the mid-upper 90s from both sides.'

"I don't even know what that does to you when you go out — and eventually we're going to build pitch count — when you go out and get into the 90- to 100-pitch range, like he will in the summer. What does that do to your body to then bounce back and have a left-handed outing?"

To begin the season, the Mariners are scheduling Cijntje as a right-handed starting pitcher every Saturday, and then sprinkling in one relief appearance as a left-handed thrower on Wednesday.

In his first two professional starts — primarily throwing right-handed — Cijntje pitched seven scoreless innings for the AquaSox. He allowed just two hits with 10 strikeouts and four walks, and he has touched 100 mph throwing right-handed.

In his first two relief appearances — throwing left-handed — he has allowed five runs over 1 2/3 innings, with three strikeouts, four walks and one home run allowed.

"From the right side he's been phenomenal, which is the side he's spent the most time on," Dipoto said. "And when he's flipped left, it's been a little bit of a tougher transition. ... We're going to continue to try to introduce like one reliever outing in between (starts), where he gets 20 pitches, 25 pitches as a lefty, to make sure we're not losing that part of what is a super special skill set."

As part of Cijntje's development, the Mariners have asked him to pitch right-handed to some left-handed batters — not to simply rely on the left-on-left platoon advantage every time, which is what he did in college at Mississippi State, Dipoto said.

"I think the thing that we need to find out as we get further out into the water is how well he recovers, how well he bounces back," Dipoto said. "And I don't even know if he knows that yet."

This month Cijntje debuted in the Baseball America Top 100 prospect rankings (at No. 100), one of nine Mariners prospects on the list.

If Cijntje stuck strictly as a starting pitcher, Dipoto suggested the switch-pitcher could move quickly through the minors and arrive in Seattle fairly quickly.

But the Mariners don't want to limit Cijntje, either.

"If he just does this for a couple of years, he'll be in the big leagues simply because he's putting the hitter in a very difficult spot, instead of developing his own (skill set), which is what we're trying to do," Dipoto said. "I think if we just made him a right-handed starter, with what we're seeing now, the pitch development relative to command, it's live. It's really kind of special.

"But why would we want to give up the chance to develop and explore what is really a one-of-a-kind skill set?"

The Mariners are dreaming of the possibilities, banking on their pitching-development pedigree while embarking on something entirely new.

"It's such an unbelievable advantage if he and we are able to kind of bring it to the end of the road as a big leaguer," Dipoto said. "If he does both of these things, it's tough to imagine. Like, I can't even imagine how much fun we would have with that skill set."

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