PEORIA, Ariz. -- Every year it seems the Mariners manage to uncover a previously unheralded, hard-throwing young reliever ready to rise quickly through the system. And this spring's candidate could well be big Art Warren, a strapping 24-year-old who has opened eyes with his mature presence and upper-90s fastball.
Warren is another converted reliever -- similar to previous success stories Edwin Diaz and Dan Altavilla -- who had a breakthrough second half last year in Class-A Advanced Modesto in his first full season out of the bullpen.
After being drafted in the 23rd round in 2015 out of Division II Ashland University in Ohio, Warren was getting decent results in Low-A ball as a starter with an 88-92 mph fastball. But he quickly worked himself into the closer's role for Modesto and then was lights out after getting invited to the Arizona Fall League.
"Very impressive," manager Scott Servais said. "This is a guy who kind of figured it out the second half of the season last year. He was dominant in helping Modesto win the Cal League, he goes into the Fall League and didn't give up a run. That's when I started to pay attention."
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Warren has been slowed this spring by a sore right hip flexor, but made his debut on Tuesday and while he allowed a pair of singles, the 6-foot-3, 230-pounder struck out the other three batters he faced, including his final victim on a 99 mph fastball on the corner.
Warren followed that with a 1-2-3 ninth in Saturday's 5-2 victory over the Reds.
"He's got weapons," Servais said. "He doesn't just throw hard. He's got a real slider and curveball in there. I like the demeanor and makeup. He's physical and it looks like he could hold up over the course of a long season."

Warren said his velocity has increased in part because he's no longer pacing himself as a starter, but also because he's gotten bigger and stronger during the past year after coming to Arizona in the 2017 offseason to commit fully to his career.
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"Honestly, when I moved out here to work out, giving up time with my family and girlfriend coming off my first pro season, my mentality changed," the Ohio native said. "I knew I had to do something different, I had to push myself more to get where I want to be. There's that age-old saying, when you're done playing you don't want to ask yourself, 'What if?' So, that was my thought process. And I got bigger, stronger and my velo ticked up."
So did his development status as he's elevated now to the Mariners' No. 8 prospect per MLB Pipeline and has clearly caught the Mariners' attention.
Having never pitched above Class-A ball, he still has a long path. He says he's just "soaking everything up like a big sponge" this spring from the veterans in camp, keeping the same approach he brought to the Fall League when he went in with eyes wide open and then opened other's eyes with his own performance.

"It took up until the All-Star break in Modesto for things to kind of click," he said. "I was working on being quick to the plate and a slide step, kind of overanalyzing myself and my mechanics. I got back to what worked for me and got comfortable in my own shoes and trusting my work ethic. I changed a little of my routine and preparation into each outing, and it just steamrolled.
"Good outings just kept piling up and before I knew it we were in the championship. It's tough because you don't want to think too much into it when you're on a streak, so it's just a blur, a cloud of smoke; you just keep riding through it. You don't change what you're doing, you just roll with what's working.
"So I carried that into the Fall League," he said. "Going to play with all those top-prospect guys and I'm just a smaller D-2 guy. I went in there with open ears, same mentality as I have here, and learned from those guys. It's all just a really good experience."