Stephen Strasburg to undergo MRI

PHILADELPHIA -- Stephen Strasburg's impact on the Washington Nationals' present and future is so profound, the team has grown accustomed to treating every twitch, flinch or hiccup with the urgency befitting a three-alarm fire.

So when Strasburg grimaced and flapped his right arm in discomfort after throwing a 90 mph changeup to Philadelphia's Domonic Brown in the fifth inning Saturday night, manager Jim Riggleman, pitching coach Steve McCatty and trainer Lee Kuntz all hot-footed it to the mound for a closer look. Seconds later, the entire Washington infield had gathered, either out of curiosity or to provide moral support -- or both.

If the Nationals could have summoned 93-year-old former surgeon general C. Everett Koop on speed dial, they probably would have roused him from bed for an opinion, too.

The official update finally came after the game, when Nationals general manager Mike Rizzo told reporters that Strasburg has a strained flexor tendon in his forearm and will undergo an MRI on Sunday in Washington. Until then, the team is going to refrain from speculating on the severity of the injury or what it could mean for Strasburg's workload the rest of this season.

"You're always concerned when a pitcher leaves in the middle of a game," Rizzo said, "but we're going to see what the MRI says and react accordingly."

How serious is the injury? Phillies outfielder Shane Victorino told reporters that plate umpire Brian O'Nora "said he heard something pop" when Strasburg threw the pitch. But Brown, who was standing 60 feet away from Strasburg in the batter's box, said he heard no such thing.

And the Nationals had to be encouraged by the initial reaction from Strasburg, who lobbied Riggleman to stay in the game. Given that Strasburg knows his body better than anyone else, that has to be considered a good sign.

"I'm not going to speculate on what it is," Nationals first baseman Adam Dunn said. "Obviously it scared him. But after seeing his reaction, I would probably say it's not too serious. If this is Game 1, 2, 3, 4, 5, 6 or 7 of the World Series, he probably stays in. But it's not."

Now that the euphoria of Strasburg's 14-strikeout debut against Pittsburgh in early June has faded, his rookie year in Washington has become an exercise in collective breath-holding. He went on the disabled list with shoulder inflammation in July, and the Nationals have determined that they're going to shut him down after 160 innings. Strasburg is at 123 1/3 innings between the minors and majors, so he only has about five starts left even in a best-case scenario.

Rizzo and Riggleman have seen enough pitching injury tales -- from Ben McDonald and Paul Wilson to Kris Benson to Mark Prior -- to know even "sure thing" No. 1 draft picks come with significant risk. Throw that much torque and arm speed into one fastball-flinging package, and the same attributes that make Strasburg so challenging to hit make scenarios like the one Saturday night almost inevitable.

"You have these great pitchers and you've got to take them [in the draft]," Riggleman said. "But they're vulnerable, and we try to protect them as best we can."

At the moment, Strasburg resides in a different club. Like Billy Wagner, Andy Pettitte, Ben Sheets, Jason Jennings and J.A. Happ before him, he's feeling discomfort in his flexor tendon. Whether it's just a passing scare or a harbinger of full-blown elbow issues is a question only time and his personal physiology can answer.

Washington fans might eventually grow tired of sweating out every Strasburg start, and for each supporter who praises the Nationals' careful handling of Strasburg, there's a cranky old-school type who'll criticize the team for coddling him. The Nationals paid Strasburg $15.1 million out of the draft in 2009 and they understand his value as far as wins and losses, gate receipts and the overall image of the franchise. So they'll exercise caution at every turn and hope for a clean MRI on Sunday and a positive prognosis long-term.

"He's a gamer, man. That's one thing I've learned about him," Dunn said. "But if he ain't feeling right, get him out of there. Guys like this just don't come around very often."

Jerry Crasnick is a senior baseball writer for ESPN.com.