"[Hughes] showed some improvement, although I do think there is more room for improvement," Pirates manager Clint Hurdle said last week. "But he is better than he was when he got [to Indianapolis earlier in the season]."
Hughes is 1-2 with a 4.61 ERA in 13 big leagues appearances this year, but didn't see the field during his latest two-game stint in Pittsburgh. He was originally optioned to Indianapolis on May 3 to make room for Contreras after earning a spot on the Opening Day roster.
"I've got to stay positive and get better," Hughes said. "That's how it works."
Contreras has pitched four innings this year and given up five hits, two runs and a walk while striking out four.
Hughes said he has about 72 hours to get back to Indianapolis, where he hasn't given up a run in 6 2/3 innings this season.
"But I won't take that [long]," he said. "I want to get back to playing."
Steven Petrella is an associate reporter for MLB.com.