CHICAGO -- Ethan Roberts is a prime example of what people around the Cubs mean when they mention developing at the Major League level. The young reliever has the makings of a dominant arm and is gaining experience on baseball's toughest stage.

Another lesson arrived in a 4-3 loss to the Pirates on Thursday night, when Roberts was given the opportunity to escape a jam of his making. Manager David Ross loosened the rope, let Roberts face one more batter, Yoshi Tsutsugo, and the game swung in the wrong direction.

"He's taking some bumps and bruises," Ross said, "and trying to establish himself as a big league reliever. I think that stuff takes time and you've got to go through some rough environments and try to get out of those."

Roberts has been one of the feel-good stories of the season's early going for the Cubs. The 24-year-old righty was added to the 40-man roster over the offseason and made the Opening Day roster -- complete with a made-for-TV moment in the dugout with Ross -- near the end of camp.

This came after Roberts racked up 72 strikeouts against 17 walks in 54 innings between Double-A Tennessee and Triple-A Iowa last season. Then, toward the end of Spring Training, the righty began testing out a sweeping slider, which has topped 3,000 rpm in spin rate and generated nearly two feet of horizontal movement.

Even with all of that working in Roberts' favor, he is learning valuable lessons in the big leagues on the fly.

"I'm going to learn every time I get out there," Roberts said. "I think the biggest thing that I want to get over is just being confident in myself. It's a hard game. If it was easy, everybody would do it. You hear that all the time, but it's tough. It's an adjustment."

Against the Pirates, Ross handed Roberts the ball in the fifth inning with the Cubs holding a 3-2 lead. After striking out Roberto Pérez, the reliever allowed a slapped double to left to Hoy Park. It was a tip-your-cap swing on a cutter below the zone.

Roberts followed that with a called strikeout against Bryan Reynolds and a four-pitch walk issued to Ke'Bryan Hayes. That free pass to load the bases is where Roberts' outing really took a turn. He tried to catch the edge of the zone twice with his new slider, but missed.

"I missed some sliders on Hayes," Roberts said. "If I throw those for strikes, that whole at-bat's a different story. Again, that's a pitch I've been throwing for three weeks. So, it's just an adjustment period for me."

That set up the night's momentum-swinging at-bat with Tsutsugo.

"I tried to give him that last hitter there," Ross said.

Roberts started the at-bat with consecutive cut fastballs that clipped the outer edge of the strike zone for called strikes.

"First two pitches were executed perfect to him," Pirates manager Derek Shelton said.

Instead of mixing things up, Roberts threw the pitch four more times to the same area. Tsutsugo fouled off a pair before the battle's fifth pitch sailed outside for a ball.

"In my head, I see a hole up in that upper-right box. That corner," Roberts said. "I shook off one or two curveballs in that at-bat to get to a fastball again. That's on me. But I'm never going to not be convicted in what I throw.

"And I was convicted in throwing those fastballs. It's just, sometimes you get clipped."

The last fastball in the sequence was not elevated enough and Tsutsugo sliced it into left for a go-ahead, two-run double. Ross emerged from the dugout and took the ball from Roberts, who still pointed skyward on his walk off the field. Once in the dugout, teammate Justin Steele leaned over the bench and gave the reliever a supportive slap on the back.

It was another learning experience -- another part of Roberts' ongoing development. And he is happy to have the chance to figure things out on the Major League stage.

"Absolutely. It's sped up almost two times the learning curve," he said. "I'm learning it way, way, way, way faster than I would have if I was in Triple-A. And I learned a lot in Triple-A last year, man. I learned pitching to a scouting report and a lot of stuff that a lot of guys helped me with.

"But here, yeah, I've learned that my stuff plays. But I just have to throw it in the zone. I've got to stop nibbling. I've got to be confident in myself."