The Milwaukee Brewers outfield group is currently down a few of their core players. Blake Perkins has been injured since spring training as he sustained a tibia fracture. Garrett Mitchell is nursing an oblique strain. Lastly, Sal Frelick is dealing with a knee issue, but appears to have avoided another major injury.
Sal Frelick had a MRI done on his knee

On Sunday against the Cubs, Frelick injured his knee during an at-bat. He told ESPN that “My whole body rotated, but the spike on my toe stayed in the dirt. My foot almost came out of my shoe. I tried to play another inning, but my knee was blowing up on me.”
A MRI was performed afterwards that showed “a ton of inflammation”. David Gasper of Athlon Sports reported that Frelick’s knee was not doing too much better on Monday, but Tuesday he was able to jog around, do a dynamic work out, and took some swings in the cage. Right now, he is aiming for a return to game action on Friday.
The Milwaukee Brewers and Sal Frelick believe he avoided another major knee injury

In college, Frelick had his left knee operated on two times due to meniscus issues. While his most recent MRI did not show any new tears, Frelick described the injury as a meniscus sprain. The belief is that once his knee is back to feeling better, he can safely return to play.
Milwaukee will be finishing up a series against the Houston Astros on Wednesday and then have Thursday off. Hopefully Frelick will be able to make a return to the Brewers lineup on Friday. With Mitchell and Perkins out, Frelick returning sooner rather than later will be critical to maintaining a strong lineup.