"It's just inflamed, so we just decided to go ahead and put him on the DL and get it right," Williams said. "Over the last few days, it's just been really sore."
The amount of time McLouth will miss is still to be determined, but Williams didn't rule out the injury keeping the outfielder on the sideline until September. For now, McLouth won't throw for five days, according to general manager Mike Rizzo.
"We'll see how he reacts," Williams said. "The first thing is to get him that anti-inflammatory shot and calm him down, and then see where we're at. But he should be good. It's not something that should last too long."
Daniel Popper is an associate reporter for MLB.com. This story was not subject to the approval of Major League Baseball or its clubs.