Through three starts, the 23-year-old Harben has allowed five runs and 10 hits in seven innings combined. He has seven strikeouts to four walks.
"I like what I've seen from three starts," he said. "We're not going with too many pitches in these games. He started off at 30 pitches (per game) and is up to about 50 pitches right now. I think he made 53 pitches on Saturday, so next time out we'll try to stretch him out to four innings or 60 to 65 pitches."
At Double-A New Britain of the Eastern League this past season, the 6'5" Harben was 4-9 with a 3.96 ERA in 122 2/3 innings -- primarily as a starter. He fanned 74 and walked 67.
Taken by the Twins in the 15th round of the 2002 draft, Harben won 10 games with Class A Fort Myers of the Florida State League in 2005, posting a 2.66 ERA with 119 strikeouts in 135-plus innings in his best season to date.
He was one of the Twins' original prospects slated to attend this year's edition of the Fall League and took the place of right-hander Grant Johnson on the Sox roster following the trade. (The Solar Sox houses prospects from both the Cubs and Twins in addition to the Dodgers, Astros and Mets.)
"I think he's going to be fine," Listach said.
Of the remaining six Cubs prospects in the Fall League, Listach said, "They're doing fine. (Jake) Fox had a rough day at the plate Saturday, but he's been doing fine. He picked off two guys on the bases, threw a guy out at second trying to steal so his defense is getting better."
"Scotty Moore has been playing quite a bit DH'ing, playing first base and third base, so he's been doing fine, too," Listach said.
And Eric Patterson "did a nice job (Monday)," said Listach. "He was 1-for-3 with a walk and a stolen base. They're all doing fairly well."
Updated Fall League Stats (through Oct. 24)