It didn’t take long for the stitching on Jimmy Nelson’s new uniform pant leg to be stressed to the max, as the 6-foot, 5-inch, 245-pound right-hander rolled them up above the knees to put his socks and cleats on when he was called up to the Milwaukee Brewers on Sept. 1.

Johnny Hellweg is thinner, with his Brewers-issued warmup shirt and 209 pounds hanging a bit more loosely on his 6-9 frame, but Milwaukee Brewers hope that the final stretch of the 2013 regular season gives general manager Doug Melvin and manager Ron Roenicke an idea as to whether or not their top two pitching prospects will do more than just cut imposing figures on the mound.

"Some of these young guys we’ve seen this year, some of these young guys that have come up and they’ve pitched as good as anybody in the league – there’s some really dynamic, young, starters in our division," Roenicke said. "So, you hope that’s what’s going to happen. But a lot of times, when guys aren’t completely polished in Triple A, they come up and they try to find out what to do, physically how to pitch guys and mentally what you need to think about to get these guys out."

The pair of 24-year-old rookies have accomplished quite a bit in their short time in the Brewers organization.

Hellweg, acquired in the Zack Greinke trade last summer, was named the 2013 Pacific Coast League Pitcher of the Year for Class AAA Nashville. Nelson, a 2010 second round draft pick out of the University of Alabama, represented the organization in the Futures Game at Citi Field during All-Star weekend in July.

Now, they have an opportunity to enter the race to fill out the back end of the Brewers rotation in 2014 behind Kyle Lohse, Yovani Gallardo and Wily Peralta.

But, it won’t come without growing pains. Roenicke remembers a time when organizations wanted minor leagues to reach 100 starts before they were even considered for a call up.

Nashville pitching coach Fred Dabney, who pitched in 301 minor league games over nine seasons of affiliated ball from 1988 to 1996 agreed – and cautioned that even though Nelson and Hellweg are wearing Brewers uniforms, they’re not finished products.

"The game has changed from 15 to 20 years ago, or 25 years ago, and that’s what people need to realize – just because they’re up in the big leagues doesn’t mean they’re not continuing to develop and work on things that they need to do to have success," Dabney said.

"You’re talking about two young pitchers. In my opinion, these guys are still babies. You look at ‘em and they’ve got the baby faces. Just take away the age, but some people mature differently than others. Some kid that’s 18 or 19 years old that’s very mature and then you take some 22 to 25 year olds and they’re not as mature as the 18 year old. Everybody develops and matures at their own pace."

Hellweg will be given first crack to make the starting rotation, as he joined a six-man rotation with his start on Saturday in Chicago. Nelson, who logged a career-high 152 1/3 innings between Class AA Huntsville and Nashville, will be used out of the bullpen.

The pair bring power arms to the rotation, but Hellweg is learning that unleashing it isn’t as important as he first thought.

In his first four years of professional baseball from 2008-11, Hellweg averaged 11.5 strikeouts per nine innings. In his last two seasons, he decided to dial it back and use his fastball to coax easier outs, averaging just over 6 strikeouts per nine innings. He went 2-1 with a 2.70 in seven starts with Class AA Huntsville after coming over from the Angels, and this year he posted a 12-5 record with a 3.15 earned run average in 125 2/3 innings at Nashville.

"He had a tremendous year and it’s still not even close to what this kid could be," Dabney said. "He has so much potential and ability. It’s through the roof. At times his stuff is so good he was able to get by at times with a couple of mistakes. He’s a work in progress – it was his first year in Triple A, in terms of a full season, and he was awesome."

That has allowed the lanky kid picked in the 16th round of the 2008 draft out of St. Dominic High School in O’Fallon, Mo. to get his first two shots with the Brewers this summer. His first call-up in late June and early July was unsuccessful, as he was rocked for 20 runs (13 earned) in just 10 2/3 innings. He gave up 19 hits and walked another 13 in four games (three starts) for a 10.97 ERA.

In his first start since being called back up, Hellweg gave up three earned runs (four total) in six innings against Chicago on Saturday.

"Hellweg’s got good stuff, man," Nelson said of his teammate. "He’s learned how to pitch. He’s learned how to add and subtract from his fastball down there. He doesn’t have to just try and blow by guys. He does a good job of using his fastball as more than one pitch. He uses it as several different pitches just changing the speeds all night long."

Hellweg hasn’t really missed too many bats while a member of the Brewers – he’s struck out just four in 16 2/3 innings – but when he returned to the minors following his first stint in Milwaukee, he worked on his command and consistency on the inside part of the plate against left-handed batters, along with his breaking ball. Due to that work, he anticipates his final starts down the stretch to be more productive than his first turn through the majors.

So does Roenicke.

"I want to see what he’s all about," he said. "I want to see him throw the same way he does there, see what happens. For him, yeah, this is an important time. He can make a certain impression on us going into next year that’s really good. I don’t think if it doesn’t go great it’s so much of a huge negative to it because we know there are lots of guys that take a little longer to develop. But I think we’ve seen, because of the year he’s had, what could be. If it doesn’t go well here he’ll try and make our team next year and if he doesn’t then he goes back there and starts again."

For his part, Hellweg is ready to make that impression.

"Just improve on everything I did last time, kind of carry over what I was doing in Nashville all year to here and I think being here before makes that transition a little bit easier," he said. "I kind of know what I’m going to be dealing with, all the outside stuff off the field and kind of some of the on field stuff that goes unspoken as well.

"(PCL Pitcher of the Year) shows I did what I need to in Triple A and now it’s time to do that here. It’s still the minor leagues down there. It was Triple A but it gives you a little confidence boost coming up here and getting another shot."

Nelson made his major league debut on Sept. 6 in Chicago, throwing just 19 pitches in two perfect innings of relief work. Of those 19 pitches, 12 were strikes, but all of his outs came off contact. Like Hellweg, Nelson focused more on strike-throwing than striking batters out.

He set out with the goal of reducing his walk rate from 7.2 batters per nine innings in 10 starts in Hunstville in 2012 and did just that, walking just 3.8 batters per nine innings in 27 starts between Huntsville and Nashville this summer, where he went 10-10 with a 3.25 ERA.

"I gave up a few more hits and stuff this year but that’s going to happen when you’re in the zone more," he said. "I’ll take a few more hits than walks any day."

"I’ve had a good season. I’ve improved in a few areas that I lacked in last year, going from high A to double A last year so I touched on a few things there. There’s a few more things to work on. There’s always something to work on. I’m going to continue to try to work on those things because you’re competing and trying to help us win."

While coming out of the bullpen will require a slight mental adjustment – Nelson has started 75 of his 88 career games in the minors – fatigue won’t be an issue.

"No, if you’re tired and you get called up you’re not tired," he said. "It’s a little energizing. I felt good this year. I know last year I missed some time at the end of the year but I worked hard this offseason on my conditioning and working out and everything and it’s paid off and I feel good."

Dabney said Nelson "attacked" his consistency issues when he arrived in Nashville – whether it be in his mechanics or his third pitch, a changeup, to compliment two-seam and four-seam fastballs and his top end slider.

The pair earned their promotions to Milwaukee. Now it’s just a matter of if they stick for the long haul.

"Both those guys, when they take the mound, they do have an aura about ‘em," Dabney said.

"I do know when they step on the mound, other teams are not excited about facing them. There’s times where players on the other team would go over there to coach first base and go ‘you know what, I’m glad I’m getting the day off today. Facing this guy? I want no part of ‘em.’ Both of those guys, with their ability and the stuff that they have, when they are at their best nobody wants to stand in there and face those guys, I’ll tell you that."