The Nationals made the long-delayed declaration Tuesday that second baseman Danny Espinosa needs some to time to heal and get his swing back.
Also, starter Stephen Strasburg is dealing with a slight strain in his lat and will throw a bullpen session Wednesday to see if he can make a start on Saturday.
Werth was activated from the 15-day disabled list and hit second and played right field for Tuesday night's series opener against the New York Mets. Werth had been sidelined since May 2 since with a strained right hamstring and recently finished a six-game rehab assignment with Class-A Potomac, where he batted .556 with two home runs and eight RBIs.
The Nationals hope that Werth can restore some punch to a team that entered Tuesday's play batting .229 with a majors-worst .287 on-base percentage.
Werth's return was expected. The other moves weren't.
Espinosa was placed on the 15-day disabled list, a move he's been resisting for most of the season even though he's hitting .158. He has a small fracture in his right wrist and is feeling the effects of playing last season with a torn rotator cuff. Espinosa was so upset when he heard the news that he cleared out his locker completely, not the norm for someone placed on the DL.
"He's been playing through pain for the last year or so," general manager Mike Rizzo said. "And it finally got to the point where he was not performing, and he was injured."
Espinosa will see a hand specialist Wednesday and will have MRIs on both his wrist and shoulder. Rizzo didn't rule out optioning Espinosa to the minors at some point.
"We're certainly going to be putting him in a position to get his feet on the ground and to get his rhythm back as a hitter, mechanically and mentally," Rizzo said.
With Espinosa gone, top prospect Anthony Rendon could be taking over at second base on a daily basis. Rendon was recalled from Triple-A Syracuse, where he had just arrived after a promotion from Double-A over the weekend.
Rendon didn't get much sleep Monday night because of the sudden move to Washington, so manager Davey Johnson started Steve Lombardozzi on Tuesday. Rendon has been working on occasion at second base in the minors since the Nationals drafted him at No. 6 overall in 2011, relearning the position after playing third in college at Rice.
"It was actually my first position growing up. I was the small guy on the team, so they just put me at second base," Rendon said. "I guess it kind of brings back memories."
Rendon's first stint with the big club came earlier this season when third baseman Ryan Zimmerman was on the DL. Rendon hit .240 with one RBI in eight games.
The Nationals' other moves involved the bullpen. Right-hander Henry Rodriguez and left-hander Zach Duke were designated for assignment, and left-hander Ian Krol had his contract purchased from Double-A Harrisburg.
"The two guys weren't performing," Rizzo said.
The hard-throwing Rodriguez, who regularly hits 100 mph on the radar gun, was 0-1 with a 4.00 ERA in 17 appearances this season. Duke was 1-1 with an 8.71 ERA in 12 games.
"On occasion he could dominate a baseball game," Rizzo said of Rodriguez. "We were trying to be as patient as we could with him, but in the situation we're in now, it was time for us -- it's a performance league."
Rodriguez, packing his belongings in a busy round of comings-and-goings three hours before the game, said he was the victim of a "little bit of bad luck."
"I look at my videos and the strike zone -- I throw a pitch first strike, and the umpire don't call it," he said. "That put me behind the hitter in the count. ... I feel good, and I'm waiting for other teams to give me an opportunity."
Krol was acquired from the Oakland A's on March 20, competing the trade in which the Nationals received right-handers A.J. Cole and Blake Treinen in exchange for outfielder Michael Morse. Krol had an 0.69 ERA in 21 relief appearances with Harrisburg.
Rizzo said the moves weren't some sort of "jolt scenario" to send a message to the team, but they do reflect the current disappointing state of a preseason World Series favorite.
"Decisions would be different if we had a full healthy team throughout the whole season and we were hitting on all cylinders," Rizzo said. "But we're not healthy. We're trying to piece together a lineup to help us scratch out and score enough runs to win some games."
Information from The Associated Press was used in this report.