CLEVELAND -- As rookie lefty Reid Detmers is finding out, there’s a learning curve when you first get called up to the Majors.

Detmers, coming off his first career win in a solid start against the Astros, couldn’t replicate that success against the Indians on Saturday, as he lasted just 3 2/3 innings in a 5-1 loss at Progressive Field. Detmers was charged with three runs on seven hits and three walks and has a 7.11 ERA in four starts this season.

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"There's a lot of learning,” Detmers said. “I've only made four starts up here, so a lot of room left. I'm just gonna go out there and be myself, not gonna worry about anything too much besides just working on stuff I know I can fix. Other than that, just go out there and compete. At the end of the day, that's all you can do."

Detmers is still expected to have a bright future. He was ranked as the club’s No. 1 prospect by MLB Pipeline on Thursday and as the No. 24 overall prospect in baseball. The 22-year-old ascended quickly to the Majors after being selected with the No. 10 overall pick in the 2020 MLB Draft, and he’s now trying to figure out how to adjust to big league hitters.

“They hit mistakes,” Detmers said. “"That's going to be the focus this week, just hitting spots. I've got to work on some stuff during my bullpen sessions this week and just pound the zone. Just work on some small stuff and locating, which is the main thing."

The lefty found himself in trouble most of the afternoon, including in his first inning. Detmers gave up a one-out single to Amed Rosario, and José Ramírez followed with a double off the left-field wall. But left fielder Justin Upton and second baseman David Fletcher combined for a strong relay to throw Rosario out at home as he tried to score from first.

"J-Up missed [José] Iglesias but hit Fletch right in the chest, and he made a perfect throw to the plate again,” manager Joe Maddon said. “Listen, I'm telling you, [Fletcher is] the best defender in the league. I don't care. You can talk any position you want. He's the best defender in the league and I see it every night. He needs to win a Gold Glove."

Detmers then walked the next two batters he faced but worked out of the jam by getting Bradley Zimmer to ground out to second base on a nice play from Fletcher, who had to play a tricky hop.

Detmers bounced back with a 1-2-3 second inning but ran into more issues in the third against the top of the lineup. Myles Straw singled on an 0-2 changeup and Rosario followed with a single up the middle that hit off the mound. Ramírez then unloaded on a first-pitch curveball for a three-run homer. Homers have been an issue for Detmers in the early going; he's served up five through his first 19 innings.

“I wanted to throw that pitch but I just didn’t hit my spot,” Detmers said. “If I want to throw a first-pitch breaking ball to him, it has to be down in the zone. It can't be hanging up in the zone. So that's all it really was. Just a hanging breaking ball and he saw it and hit it."

He also gave up a double to Oscar Mercado and an infield single to Owen Miller in the inning but got Austin Hedges to pop up to get out of the jam without any further damage. Detmers retired the first two batters he faced in the fourth, but he was pulled after walking Rosario so that he wouldn’t have to face Ramírez again. Reliever Andrew Wantz came in and got Ramírez to fly out to right to begin 1 2/3 scoreless frames.

Despite the results, Detmers still registered a respectable 15 swings and misses among his 70 pitches. He got seven whiffs with his fastball and six with his slider, showing that his stuff does play in the Majors, even if it was a bit down on Saturday.

“He just didn't have his best stuff from the beginning,” Maddon said. “I liked the slider today. He put a couple of his changeups in play. His velocity wasn't heavy. His curveball was just OK. He has a better one than that. He just really didn't have his better stuff. There was no reason to stretch it at that point. He was at 70 pitches. We were in that part of the game where he had nothing to gain."