Workman allowed eight hits and three runs over seven innings in Boston's 8-3 loss on Tuesday to the White Sox.
"Definitely it's not ideal," Workman said. "It's not what I was hoping to hear after the game. But it's part of it. I just gotta keep getting my work in, keep getting better, and get ready to go again."
The 25-year-old has pitched out of the bullpen and as a starter this season, posting a 4.13 ERA with 41 strikeouts and 19 walks in 52 and 1/3 innings.
The move cleared a roster spot for right-hander Rubby De La Rosa, who is scheduled to start Wednesday.
-- Chris Johnson