They are flipping the switch as we speak. Strasburg is 15-6 with a 3.14 ERA, and will finish with those numbers. Strasburg was hit pretty solidly by the Marlins last night (the Nationals lost 9-7 in 10 innings), and today, manager Davey Johnson told the media it would be Strasburg's final start of the season.
The Nationals had planned to start Strasburg against the Mets on Wednesday, but Johnson felt that anxiety over being shut down—over "letting teammates down," according to The Washington Post—had started to hurt Strasburg's game. The Post's Adam Kilgore also said Johnson thought the media had gotten into Strasburg's head:
Davey Johnson made the decision on Strasburg. He believed the media distraction had become too much and affected Strasburg's performance.— Adam Kilgore (@AdamKilgoreWP) September 8, 2012
For his part, Strasburg said he was just having trouble locating his fastball. The Nationals will go from having the best starting rotation ERA in baseball with Strasburg, to still having the best starting rotation ERA in baseball without him. In far more important news, the Cubs are shutting down Jeff Samardzija.
Stephen Strasburg Shut Down For The Season [The Washington Post]