Werth's rehab is expected to last two to three months, according to Rosenthal. The veteran dealt with shoulder soreness during the 2014 season and had to receive cortisone shots at times.
The 35-year-old hit .292 with 16 home runs, 82 RBI and a .394 on-base percentage last season. Werth has spent the last four years with the Nationals and has a career .276 average with 186 home runs over his 12-year career.
In December, Werth was found guilty by a judge for reckless driving and was sentenced to 10 days in jail with 170 days suspended. He is expected to serve five of the days, and his attorney planned to appeal the conviction.
Washington went 96-66 last season and won the NL East. They lost to the San Francisco Giants in the NLDS.
- Molly Geary