PEORIA, Ariz. -- The White Sox have an important decision to make some time before the end of Spring Training, regarding how to grow top pitching prospect Aaron Poreda.

It's not a decision focused on the best way of adding bulk to Poreda's 6-foot-6, 240-pound frame. Instead, the onus falls upon how to best develop Poreda as a pitcher and as a Major League player.

"He could pitch in the big leagues now in a bullpen type of role," said White Sox general manager Ken Williams. "We have to make a decision if we want to continue to grow him as a starter at the Minor League level or let him grow as a starter through the Major League bullpen, which we've done before."

Williams pointed out past White Sox success stories of building a starter through primarily relief work at the outset, such as Mark Buehrle in 2000, Gavin Floyd to some extent in 2007 and Jon Garland in 2001. At 22, the White Sox top pick in the 2007 First-Year Player Draft might have the best raw stuff of this select group.

Poreda effortlessly throws his fastball in the mid-90s, but the story for the left-hander would be upgrading his secondary stuff. Williams believes this present improvement is more evident during Poreda's side sessions, but pitching coach Don Cooper also called for 17 sliders during the big man's four-inning appearance on March 9 against the Indians.

"It's important to be using it in the game," Poreda said. "Coop made sure that [catcher Tyler] Flowers called a lot of sliders to work on that stuff, and it was nice. The first couple weren't that great, but the more I threw, the more I get comfortable with it and the better it's going to be.

"I've been working on making it the same delivery as my fastball and really getting the feel for it. It's coming along nicely."

Thinking of his slider's improvement brought a smile to Poreda's face, leading him to talk about a second secondary part of his repertoire.

"My change is coming along nicely, too," Poreda said. "I got a strikeout with it looking [against Cleveland], and I don't think it has every happened before in my career as a pitcher. It's moving along."

Aside from a "B" game start against the Dodgers, Poreda's three Cactus League appearances have all come in relief. He allowed one run over three innings against the Cubs in Las Vegas, calling his assistance in that particular victory his "highlight of Spring Training so far." Poreda yielded one run in four innings against the Indians, fanning three, and threw two scoreless innings against the Rangers on Saturday at Camelback Ranch.

That last outing marked Poreda's first walk allowed in nine innings, to go with six strikeouts. Finding the zone was one of Poreda's main goals coming into White Sox camp, and he has proven that point even in the somewhat unfamiliar environs of relief.

"You have to keep your body hot the entire game, so I'm constantly running, stretching and waiting," said Poreda, who worked exclusively out of the bullpen during his recent stint in the Arizona Fall League. "You also get nervous, so you have to go to the bathroom four or five times.

"I'm a guy who needs to stretch a lot. So, it's definitely a little different."

Different doesn't necessarily mean bad in this situation. Poreda prefers to stay as a starter, but in the standard answer for any young player, his greatest preference is to become a Major Leaguer as quickly as possible.

Bobby Jenks, Matt Thornton, Scott Linebrink and Octavio Dotel are locks at the back end of the White Sox bullpen. Clayton Richard and Jeff Marquez are pretty close to the same certain status if Jose Contreras and Bartolo Colon break camp as part of the rotation.

That roster math leaves one spot open, if the White Sox take seven relievers, with Poreda and D.J. Carrasco standing as the prime candidates. White Sox manager Ozzie Guillen and Cooper would prefer a third lefty to join Thornton and Richard, and while outside options exist such as Will Ohman, the team has reached its spending limit at this point.

So, an already impressive Poreda will get more spring looks as the White Sox continue to decide what to do with him.

"Aaron Poreda will be getting more work because he still has a chance to come with us, for one," Cooper said. "And two, he's a part of the White Sox future. Nothing but good from him so far."

This Major League learning curve doesn't just deal with sliders and curve. According to Poreda, being part of his first big league Spring Training also has taught him about the different rules between the Minors and Majors. It's all part of the Poreda growing process.

"One thing is you can't sleep in the locker room, unless you are the oldest guy in the clubhouse," said Poreda, who said he was humorously yelled at and made fun of by his teammates following the mistake. "I made a couple of mistakes and did some things that I shouldn't have, but it's all part of the learning experience."