The butterflies, however, never showed up.
"Walking onto the field, I kept waiting to get nervous and feel those butterflies in my stomach," said Hellweg, who is ranked the Brewers' No. 3 prospect by MLB.com. "For some reason, that never sank in. It happened in every start leading up to that point in Triple-A, every start I've ever had. It never sank in when I was in the big leagues.
"It was weird."
Nobody is blaming Hellweg's lack of nerves, but in his first three Major League starts, he never showed up either. The pitcher who dominated opposing hitters at Triple-A Nashville was somebody else in Milwaukee, unfamiliar to those who watched him previously at other levels, but, more importantly, unfamiliar to himself.
"I didn't throw like I had been," said Hellweg, who was picked in the 16th round of the 2008 First-Year Player Draft by the Angels and eventually traded to the Brewers as part of last year's deal involving Zack Greinke. "I tried to do a little too much at times and not enough the other times. It just, it didn't go very well."
Hellweg, who felt the joy of a big league callup and the pain of a demotion back to Triple-A in about a two-week span, posted a 10.97 ERA in three starts -- all losses -- and a relief appearance with the Brewers that lasted just 10 2/3 innings total. Even worse, there was little improvement in his three starts. Although Hellweg lengthened his outings from 1 2/3 innings to 3 2/3 to 4 1/3, and his earned runs went from five in his first start to three and four in his final two, respectively, his control wavered from two walks in his first outing to five walks in each of his last two.
"Some of the pitches I was getting guys out with in Triple-A wasn't working up there," said Hellweg, who noted that he felt more comfortable in his third start, although the results weren't what he wanted. "Everything kind of wasn't speeding up as much. I think that'll help my approach next time.
"When everything comes together, it'll be a lot easier and we'll get better results."
Baffling to anyone who has followed Hellweg's season is why there was a sudden drop-off when taking to a Major League mound. Sure, he was facing some of the best hitters in the world in the form of the Pirates (June 28), Mets (July 5) and Reds (July 10), and, yes, it was his first taste of the big leagues -- a typically teeth-chattering experience for a 24-year-old.
But most, including Brewers manager Ron Roenicke, feel that if Hellweg approached big league hitters the same way he does Triple-A hitters, he will be more than a serviceable Major League pitcher.
Hellweg looked so calm and collected while posting a 3.16 ERA in 22 starts and 119 2/3 innings at Nashville this season. His ERA is the second best in the Pacific Coast League, and it was even better before he allowed four earned runs in 4 2/3 innings in each of his past two starts, on Aug. 20 and Sunday.
Before Hellweg's most recent start -- a 10-5 loss to the Albuquerque Isotopes on Sunday -- he held a 2.98 ERA in 21 starts at Nashville and was one of only five pitchers with an ERA below 3.00 in the Pacific Coast League since 2007.
Hellweg's success in the Minors is what has Roenicke itching to see more of the tall, lanky right-hander.
"We want to see Hellweg," Roenicke said. "He's a guy I think has a high-end future. If he can figure it out up here, he's a guy who can be good a long time."
One Hellweg streak in particular this season opened some eyes. He turned in eight consecutive wins with the Sounds -- a streak spanning from five games before his callup and the three following his demotion. In the five games before his first start with the Brewers, Hellweg held a 0.82 ERA and a .198 batting average against. After returning back to Nashville following his Major League stint, Hellweg did not give up a run in his next three starts, which lasted six sparkling innings each. Opponents hit just .158 against him in those three games, including two extra-base hits (both doubles).
Roenicke talked about the importance of the remainder of Hellweg's 2013 season for both the young right-hander and the Brewers' future starting rotation plans.
"[Brewers general manager] Doug [Melvin] needs to know who he thinks is going to be in that rotation before we go into the offseason, to figure out whether we need to make some deals and get some people," Roenicke said.
Through as well as Hellweg has pitched at Nashville and as terribly as things went for him with the Brewers, Melvin feels the young pitcher is underappreciated by the so-called prospect experts.
"It's because he doesn't strike people out," Melvin said. "It's a statistical thing. He does have work to do, no doubt. But I think he deserves credit for the number of innings he's giving us [in Nashville]."
Although his first crack didn't pan out, Hellweg did take away some good experience for his next trip -- possibly a September callup when rosters expand to a 40-player maximum in a week. The St. Louis-area native said he was aided through his struggles by veteran pitcher Kyle Lohse and left-handed reliever Michael Gonzalez in the Brewers' clubhouse.
"Lohse is one of those guys that he seems a little bit more approachable, and I had seen him pitch well, being from St. Louis," said Hellweg, who noted Lohse and Gonzalez helped him in his approach with scouting lineups. "I kind of tried to pick [Lohse's] brain whenever I got a chance to. He was more than open to it. He ... helped me more than I would have expected.
"Mike Gonzalez as well -- when I got down, he talked to me. That made me feel a lot more comfortable. Obviously, the results still weren't what I wanted them to be, but it made me feel a lot more comfortable about being up there and about my stuff."
Hellweg said he understands the rarity of a young pitcher breaking into the league with immediate success, something Mets right-hander Matt Harvey has made look easy over the last two seasons.
"I love watching Harvey throw. ... Those guys are always fun to watch," Hellweg said. "You want that for yourself as well, but I guess that's why that's such a great story, because it doesn't happen a lot. But I'd much rather get all this stuff out of the way now than do well for a year and then run into my bumps and bruises and try to make adjustments from there. If I can get those out of the way in my first year, that would be better for me and my career."
Hellweg will get a second crack at big league hitters, maybe in the very near future. Whenever that opportunity comes, the question will still swirl around his head, butterflies or not: What pitcher will he be?