Mattingly said the fact that Ethier played with discomfort through Wednesday's doubleheader and Thursday night after a cross-country flight contributed to the day off.
"The knee has a little swelling and we've asked a lot of him," said Mattingly, who pressed Ethier into center-field duty with Matt Kemp sidelined. "He needs a day. He and Puig ran together in Pittsburgh and he hit the wall, but I don't know if that was necessarily it."
Skip Schumaker started in center Friday night and Elian Herrera was in left.
Ken Gurnick is a reporter for MLB.com. This story was not subject to the approval of Major League Baseball or its clubs.