Overshadowed by a masterful pitching performance by Cleveland Indians right-hander Zach Plesac, the anticipated debuts of prized Seattle Mariners prospects Logan Gilbert and Jarred Kelenic didn't quite play out as the team hoped Thursday night in a 5-2 loss at T-Mobile Park.

Gilbert (0-1) lasted four innings, allowing four runs on five hits, striking out five and walking none while throwing 71 pitches. Seattle was going to limit Gilbert to around 85 pitches and was hoping to get him into the fifth.

The 24-year-old right-hander threw plenty of strikes and flashed a good mix of breaking pitches to go with his fastball.

"I definitely feel like I belong here and my stuff plays up here," said Gilbert, who was ranked as the No. 43 prospect in baseball, according to ESPN's Kiley McDaniel.

Gilbert allowed two home runs -- one on a hanging slider to Franmil Reyes and another on a 94 mph fastball to Jose Ramirez after falling behind 3-1 in the count.

"As they're watching the game unfold, they realize that Logan really does lean on his fastball," Servais said of the Ramirez homer. "He truly believes in it, and he should, it's a really effective pitch. But [Ramirez] got up on top of a 3-1 fastball and that's what happens -- Jose Ramirez is really good."

Gilbert acknowledged making mistakes that cost him.

"Definitely don't get away with all the mistakes that maybe I did coming up," he said. "And of course, just falling behind in the count, they are usually gonna make you pay for it. So when I did leave pitches out over the middle of the plate, more often than not they took advantage of them."

Kelenic started in left field and batted leadoff for Seattle. He was hitless in four at-bats against Plesac, who took a no-hit bid into the eighth inning. Kelenic flied out on the first pitch of his first at-bat, with right fielder Josh Naylor falling into the stands as he caught the ball in foul territory.

Kelenic has been regarded as one of the top prospects in the minors for several years and only reinforced his status with a torrid start at Triple-A, where he hit .370 with six runs, two homers, a double and five RBIs in just six games.

The Associated Press contributed to this report.