Wang’s 30-day rehab window was set to close Aug. 11, meaning the Nationals would have had to add him to their 25-man roster or remove him from their 40-man roster on that day. With Wang re-injured and off his rehab assignment, he can remain on the disabled list for the foreseeable future, possibly until major league rosters expand Sept. 1.

Last night, Wang allowed six runs in 4 2/3 innings in his fifth start during his latest rehab tour. The Nationals placed Wang on the disabled list on July with hip tightness, which they believed to be hindering his delivery and causing his trademark sinker to drift sideways rather than dive downward.

Over four starts and three relief appearances in the majors this season, Wang has a 7.61 ERA in 23 2/3 innings with 14 walks and 12 strikeouts. Wang spent all of 2010 and most of 2011 with the Nationals rehabbing from major shoulder surgery. Wang finished last year strong, and the Nationals signed him to a one-year, $4 million contract this offseason.

Wang had a place in the Nationals’ rotation until he tore his hamstring midway through spring training. He returned in late May but never pitched as the Nationals envisioned, derailed by more injuries. Since Wang signed with the Nationals, he has started 15 games in the majors and 17 in the minors.

If Wang heals, the Nationals could still use him in September as starting depth. With Stephen Strasburg set to be shutd own at some point in early September, Wang would be additional insurance behind John Lannan in the rotation.

More from The Washington Post

Wednesday’s lineups

Roger Bernadina playing well

Ross Detwiler dominates again