Zimmerman was 13-for-58 (.224) with a home run and seven RBIs in 15 games for Washington before being placed on the DL on April 28 (retroactive to April 21) with right shoulder inflammation. The Nationals went 7-6 during Zimmerman's stint on the DL.
Werth, 32, was hitting .276 (27-for-98) with three home runs and 12 RBIs in 27 games for the Nationals before being injured while making a sliding catch in Sunday night's series finale against the Phillies.
The trip to the DL is Werth's first since 2008. He entered the season as one of just nine National Leaguers to play in at least 150 games in each of the previous three seasons.