Both moves could have ramifications on either side of the roster, with Puig joining a crowded outfield and Frias leaving a pitching staff that still needs another starter, even with left-hander Julio Urias staying in the rotation for another start after Wednesday.
Puig was hitting .237/.283/.360 with five homers and 20 RBIs in 53 games, 43 strikeouts and nine walks before being placed on the disabled list with a strained left hamstring. He played five games for Class A Rancho Cucamonga on a rehab assignment, going 9-for-24 with a homer and three walks.
"I'm working hard with the bat. I've always worked hard. I hope that this second half I will do a lot better," Puig said. "It's been hard watching from home or from the Minor Leagues and not being able to help my team."
Puig's return will push Trayce Thompson out of regular work in right field, but Thompson still figures to see plenty of time across the outfield, even though he was out of Tuesday's lineup after making 20 straight starts. Dodgers manager Dave Roberts attributed the benching not just to Puig coming back, but also to Thompson's recent cooling off at the plate.
"He earned the opportunity to play more and the at-bats have been consistent, but as I look over the last 10 days, there's more punchouts and not as much production," Roberts said. "He's seeing a lot more breaking balls in the zone now, starting in and finishing down. Again, it's that cat and mouse. When he sees something straight, he puts a good pass on that pitch."
Thompson figures to split left field duties with Howie Kendrick while occasionally spelling Puig in right and Joc Pederson in center. Scott Van Slyke and Kiké Hernandez could also see starts in left.
Frias was recalled on Sunday for long-relief coverage after Mike Bolsinger lasted just 2 2/3 innings in his start Saturday night, but he did not appear in a game. Sending a reliever down for a position player will keep the Dodgers on an eight-man bullpen while the team figures out what it will do with the rotation.
The team still hasn't determined the order of its rotation beyond the series with Washington.
Jack Baer is a reporter for MLB.com based in Los Angeles. This story was not subject to the approval of Major League Baseball or its clubs.