Knebel has been sidelined with a hamstring injury and he hasn't pitched since April 5. He had a 10.13 ERA with one save in two chances this season but saved 39 games last season with a 1.78 ERA.
Miley left his start Tuesday night with one out in the first inning because of a strained right oblique. It was his second start this season after a groin injury in spring training delayed his debut.
In other moves Wednesday, the Brewers placed infielder Nick Franklin on the 10-day disabled list with a strained right quad and recalled infielder Tyler Saladino from Triple-A Colorado Springs.