PEORIA, Ariz -- First impressions of 2018 first-round Draft pick Logan Gilbert? At 6-foot-6, he casts an imposing figure on the mound. And the 22-year-old generates a lot of power with a throwing motion that takes maximum advantage of his size.

Gilbert threw his first bullpen session on Friday under the watchful eye of manager Scott Servais and others who were getting a look at Gilbert’s mound debut in his first Major League camp. There was no one standing in the batter’s box, just Gilbert firing to catcher Cal Raleigh, his batterymate last year at Double-A Arkansas.

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But there was no mistaking the power behind Gilbert’s initial session and the reason he’s the top-ranked pitching prospect in Seattle’s system and the No. 48 overall prospect in baseball per MLB Pipeline.

“Logan’s obviously got a good arm and good stuff,” Servais said. “How his body works, he’s got big-time extension down the mound. That’s what sticks out immediately. There is going to be deception.”

Gilbert has a fastball that sits in the mid-90s, along with a slider, curve and changeup in a four-pitch mix that helped him go 10-5 with a 2.13 ERA in 26 starts last year as he sped through three Minor League levels.

But it’s the throwing motion and long extension that intrigues Servais.

“Some guys, the radar gun doesn’t tell the true story,” he said. “And we’ve seen it. We’ve seen guys come in here and throw 100 mph, but guys turn it around like it’s nothing. And we see other guys that throw 92-94 and [opposing batters] don’t hit the fastball. A lot of it is tied to deception and extension down the mound. And his extension is special. He gets down the mound, based on the [Statcast] numbers, as good as anybody in Major League [B]aseball.”

Gilbert is expected to start the season back at Arkansas and he understands this big league camp is merely his first exposure. His locker is down at the far end of the Mariners’ Spring Training clubhouse, along with the rest of the young prospects and roster long shots.

But he’s in the room now and his time isn’t likely far away.

“It was fun finally getting on the mound and seeing what it was all about,” he said. “Being with these guys in here is pretty cool. Guys like Marco [Gonzales] and [Yusei] Kikuchi that I can learn from, just try to pick up a few things here and there. And hopefully by the end of camp, it can really mold me a little bit.”

Gilbert knows he’s not going to win a job or any prizes for his first bullpen showings and was wise enough to keep things under control on Friday.

“There’s a lot of good players around here and naturally you want to compete,” Gilbert said. “So you have to tell yourself to tone it back when you need to and then there’s times to let it go. I feel pretty sharp. I’m just working on some stuff. I kind of like where I’m at. I’ve thrown quite a few bullpens and my arm is feeling pretty good.”

Two more veterans added
Right-handed starter Cody Anderson and outfielder Collin Cowgill will be the Mariners’ latest roster additions, as the two veterans have agreed to Minor League contracts and will report to big league camp as soon as they pass their physicals.

Anderson, 29, had been in the Indians' organization since being drafted in the 14th round in 2011. He’s 9-9 with a 4.76 ERA in 39 MLB games, including 26 starts, but had elbow issues last season and pitched in just five games for the Indians while posting a 9.35 ERA.

Cowgill, 33, has six years of MLB experience, but hasn’t played in the big leagues since 2016 with the Indians. He’ll add some veteran depth to an outfield group that is very young with the absence of Mitch Haniger.

Veteran outfielder Carlos Gonzalez will also be added to the roster on Monday, assuming he passes his physical when position players report to camp.

“When you sign a guy this late, a lot of times it’s for insurance purposes,” Servais said. “Having lost Mitch Haniger for a significant time, now we create opportunities for young guys. But if something happens to those guys, where are we headed from there? That’s played into some of the decision-making. Same thing on the pitching side.”

From the medical report
Right-hander Erik Swanson is being held back slightly after dealing with muscle spasms in his right shoulder three weeks ago, though the 26-year-old threw a controlled bullpen session on Saturday and didn’t appear to have any lingering issues.

“He’s just a tick behind everybody else,” Servais said. “He got out ahead of it and it’s nothing serious.”

Taijuan Walker looked strong in his first throwing session off the mound on Saturday. He doesn't appear to have any limitations after missing much of the last two seasons with elbow and shoulder issues.