Stroman, who received a cortisone shot on the hip, isn't expected to miss much action, manager David Ross said. The move is retroactive to Tuesday.
"He's still only going to miss one start with the off days we have, and he'll be able to work on some stuff with the time he's going to have down, so I thought it was an optimal time," Ross said.
Stroman, 32, is coming off a shaky performance Monday, when he was rocked for six runs in three innings in a 6-5 loss to the Cincinnati Reds. It was the third straight start in which he failed to get out of the fourth inning, a span in which he allowed 17 runs in 10 innings.
He said the hip injury has been affecting his mechanics, explaining that he was "trying to do so much without my lower half."
"It's been impacting me overall," he said. "I've been trying to change mechanics and do a lot of things to get around it. It's just at the point I couldn't do much more to change."
Stroman added: "It was beyond frustrating. When everything you're doing is not fixing it, you have to get to the root of the problem instead of going around it."
A two-time All-Star, Stroman is 10-8 with a 3.85 ERA in 23 starts this season.
In a corresponding move, the Cubs added right-handed pitcher Jose Cuas, who was acquired Monday in a trade with the Kansas City Royals, to the 26-man roster.
Cuas, 29, was 3-0 with a 4.54 ERA in 45 appearances with the Royals this season. He struck out 52 in 41⅔ innings.
ESPN's Jesse Rogers and The Associated Press contributed to this report.