Wunsch, 31, strained a muscle in his back while covering first in a June 12 game against the Giants. A few days later, he was placed on the disabled list.
The injury setback Wunsch nearly a month from his return as he didn't return to the mound till July 17. In three games with the triple-A Knights, Wunsch was 0-1 with a 5.40 ERA.
In 22 games and 15 2/3 innings, Wunsch has a 1.15 ERA. Wunsch threw 2/3 of an inning in Friday's 7-2 win, giving up no runs.
The 23-year-old Sanders compiled a 6.14 ERA in 22 innings (20 games) this season with the Sox. Sanders was called up on April 24.