TEMPE, Ariz. -- So what’s it like facing Mike Trout for the first time as an up-and-coming pitching prospect?

Mariners rookie right-hander Justin Dunn pondered the question momentarily, then noted it wasn’t exactly the first time he’d seen Trout. Turns out this was a scenario he’d been through numerous times, at least in his mind.

“I’ve faced him so many times in bullpens, in my head, drawing that whole sequence up,” Dunn said after his first real-life encounter resulted in hitting the Angels' star in the elbow with a fastball that got away from him. “I had like 17 different sequences to give to him, I just couldn’t execute them. It’s a little different when you see him in the box.”

These are the learning steps the 22-year-old Dunn and so many of his young teammates are going through this spring. Dunn, the Mariners’ No. 7 ranked prospect per MLB Pipeline, went 1 2/3 innings in Seattle's 2-0 loss to Los Angeles on Wednesday at Tempe Diablo Stadium, allowing one run on one hit with three strikeouts.

He dealt with a lot of traffic, thanks to a walk, an error and the hit by pitch to Trout. But Dunn was generally pleased with his outing, noting he was landing his breaking ball and changeup for strikes and keeping his fastball down in the zone.

The one at-bat when Dunn didn’t locate well came against Trout, when his heart no doubt was beating a little faster than normal.

“A lot of that was just me, personally,” he said. “I wanted to see how I stood up against arguably the best player in the game. I got a little ahead of myself. That was the one hitter where my misses were not nearly where I wanted them to be. But I know the corrections and next time I see him, I think we’ll have a little bit better outcome.”

This outing was about more than just facing Trout, of course. The Angels trotted out their "A" lineup and Dunn had the opportunity to pitch to Anthony Rendon, Shohei Ohtani, Albert Pujols, Justin Upton and Andrelton Simmons as well.

“I was a little juiced up going out to face that lineup,” Dunn acknowledged. “You see the names of Trout, Rendon, Upton. Everybody, top to bottom in that lineup. I was super excited to get out there. It was like my first real test to see how I could stack up against a full lineup, one through nine.”

Dunn, who pitched primarily at Double-A Arkansas last season, has an outside shot at landing a rotation berth this spring, or possibly even a long-relief spot. He’ll most likely face the Angels and Trout again at some point in a regular-season game.

When he does, he’ll know he needs to stay calm. But he doesn’t ever want to stop feeling the adrenaline that comes with competing at this level.

"I love it,” he said. “A lot of it is just breathing, trying to slow my breathing down. But the mentality of the attack and all that is where I want to be every pitch. And when you face superstars like that, it brings it up to the highest level. Now at this level it’s just learning to manage and maintain it because I’ve had success with it over the years in the Minor Leagues and in college. It’s a new stage and just trying to learn how to balance it out.”

Walker perfect in ‘B’ game

Taijuan Walker retired all seven batters he faced in an intersquad "B" game outing on the backfields at the Peoria Complex in what figures to be his final warmup before joining the Cactus League rotation early next week.

Walker has been brought along slowly this spring as he missed most of the past two seasons with the D-backs due to Tommy John surgery and a later shoulder issue. He threw 31 pitches in Wednesday’s outing.

“Finally, I feel like I can be aggressive now,” Walker said. “When I step out there I feel good and can let it loose. I don’t have any worries, nothing in the back of my head about my shoulder or elbow or anything like that. It makes it a lot easier to pitch and a lot more fun.”

Top pitching prospect Logan Gilbert also pitched in the game, throwing two scoreless frames with one hit, one walk and four strikeouts.

From the medical tent

• Right-handed reliever Sam Tuivailala threw a bullpen session on Wednesday and is progressing toward live batting practice after being held back for several weeks by a right shoulder impingement.

• Fellow reliever Matt Magill is targeted for a live batting practice session on Friday after also being slowed by a sore shoulder. Both Tuivailala and Magill would likely need to throw two live BPs before advancing to Cactus League action, which means the time frame is tightening on getting them ready in time for the regular season opener in three weeks.

• Right-hander Erik Swanson came out of his first Cactus League outing on Monday without any issues after being held back by a sore back. Manager Scott Servais said Swanson threw better as his outing progressed and he just needs more game action to get tuned up.

• Dylan Moore, sidelined the past week by a concussion, returned to action on Wednesday as he came off the bench against the Angels, replacing starter J.P. Crawford at shortstop in the sixth inning.

Up next

The Mariners continue Cactus League action on Thursday as left-hander Yusei Kikuchi takes the hill against the Padres at 12:10 p.m. PT at Peoria Stadium. San Diego will counter with righty Dinelson Lamet.