Strasburg left his Friday night start in the second inning after just 16 pitches due to tightness in his neck.
It was the second time in May that Strasburg left a game early because of discomfort. Earlier this month, he left a start after three innings after experiencing irritation underneath his shoulder blade.
The 26-year-old did not pitched more than five innings in a start in May and has only reached the fourth inning in one of his last four starts.
Strasburg is 3–5 with a 6.55 ERA and 45 strikeouts in 45 1/3 innings this season. Last year he led the National League in both games started (34) and strikeouts (242).
To replace Strasburg on the roster, the Nationals recalled right-handed pitcher Taylor Hill from Triple A Syracuse.
- Molly Geary