Strasburg said he felt "achiness" in his forearm, per Mark Zuckerman of MASNsports.com, adding he left for precautionary reasons.
Fox Sports Arizona shared when the injury likely occurred:
Matt Grace replaced the starter after just two scoreless innings, although the team does not provide injury reports until after games, per Chelsea Janes of the Washington Post. Janes also provided a note on the right-hander's stuff early against the Arizona Diamondbacks:
Entering the day, Strasburg has produced a 10-3 record with a 3.31 ERA in 19 starts.
While talented, the inability to stay healthy has been a holdup for Strasburg throughout his career. He was forced to undergo Tommy John surgery in 2010 before famously being shut down as a precaution during the 2012 season.
From there, various ailments have limited the starting pitcher to just one season of more than 200 innings, only twice reaching 30 starts.
Last year began as good as ever when Strasburg was 12-0 with a 2.62 ERA heading into the All-Star break. Unfortunately, an elbow injury once again forced him to the disabled list in August, and he ended up with a 6.15 ERA in eight starts down the stretch.
When healthy, the 29-year-old is as talented as anyone in baseball. The former No. 1 overall pick burst onto the scene in 2010 when he posted a 2.91 ERA in 12 starts. He has shown flashes of brilliance throughout his time in the league, earning three All-Star nods while once leading the league in strikeouts.
Considering Strasburg signed a seven-year extension last season worth $175 million, Washington better hope the pitcher can learn how to stay on the field.