Johnson, ranked No. 4 in the club's Minor League system, was slowed by mild shoulder tendinitis but pitched 5 1/3 shutout innings for Class A Kannapolis in his first start of the season. He gave up six runs in 4 2/3 innings against Hagerstown in his second start last week.
"Hopefully, we'll see what he did last year," White Sox director of player development Nick Capra said. "He's a big kid with a power arm. He has different breaking balls and changeups. We're excited to get him on mound against competition other than just extended [spring training] hitters."
Capra also has high hopes for the other top prospects in the organization.
Right-handed pitcher Nestor Molina, the No. 1 prospect in the organization, is 4-6 with a 5.11 ERA in his first 13 outings, which includes a 4-5 record and 4.66 ERA at Double-A Birmingham. Converted to a pitcher in 2008, Molina is in his second full season as a starter.
"Nestor has been hot and cold. He has not been bad or good," Capra said. "He's going through the normal mechanical issues but he has dynamic and electric stuff. He's a young kid that's still learning how to pitch. We're real excited about his young arm."
Capra added that outfielder Trayce Thompson, ranked No. 2, is "handling his own but he's not where we want him to be." Thompson is hitting .225 with 10 home runs and 47 RBIs in his first 63 games for Class A Advanced Winston-Salem.
"He's playing exceptional defense," Capra said. "He's still young and has lot of growing to do but he has a chance to be a good player."
Outfielder Jared Mitchell, ranked No. 18, missed the entire 2010 season because of an ankle injury but continues to make progress at Double-A, Capra said. He hit .282 with four home runs and 37 RBIs in his first 63 games with the Barons.
"He does not have a lot of games under his belt because of the injury but he's done a real nice job in Birmingham," Capra said. "He's made some adjustments to his swing and is getting better and better every day."
The White Sox are also getting an idea of what Tyler Saladino, ranked No. 7, can do at Double-A. He was also described as "hot and cold" at the plate but has been impressive on defense. Saladino hit .236 with one two home run and 23 RBIs with 23 stolen bases in his first 61 games for Birmingham.