Nats explain decision to Strasburg
Johnson was joined by general manager Mike Rizzo and pitching coach Steve McCatty.
Strasburg, who is 15-6 with a 2.94 ERA and leads the National League with 195 strikeouts, had Tommy John surgery to replace an elbow ligament two years ago.
''I'm not sure any of us understand,'' Johnson said. ''But it's the right thing to do.''
The Nationals boast the best record in the majors and lead the NL East by 6 1/2 games over Atlanta.