Stephen Strasburg exited his start on Monday with forearm tightness, something that actually means his elbow wasn't feeling 100 percent. That's a significant issue for any pitcher, but even more of one for Strasburg, who missed most of 2011 due to Tommy John surgery, and had his workload famously limited in 2012 despite the Nationals' contention. However, the Nationals are not concerned this time around, saying it was just a bit of irritation, and removal seems more precautionary than anything.
The Washington Post reports that Nationals' general manager Mike Rizzo described Strasburg's forearm as "structurally perfect" and that the irritation came from overuse of a muscle-stimulation machine prior to his start. Most importantly, Rizzo says the problem was unrelated to Strasburg's repaired elbow ligament. Strasburg's agent, Scott Boras, also chimed in to say that his client should be fine, even going so far as to say Strasburg didn't expect to miss his next start.
Given how cautious the Nationals were with their young right-hander last year, you would have to assume that taking his next turn means good things for the condition of his arm and elbow. That being said, the Post also suggests there were reasons to be concerned about Strasburg prior to Monday's removal:
Despite encouraging initial news today, troubling signs may have surfaced before Monday night. Rival evaluators had noticed a slackening of Strasburg's delivery. One National League scout, who spoke on the condition of anonymity because he is not authorized to discuss other teams' players, said Strasburg looked different on April 19 in a showdown against young Mets ace Matt Harvey.
The mechanical glitch is "possibly" an indication Strasburg was favoring part of his arm, the scout said.
So, in short: Strasburg seems to be structurally fine, and this was likely a one time thing, but scouts are concerned that he could be hurting due to a change in his mechanics. It could also just be a mechanics issue -- those can certainly happen without an injury -- but it's hard to tell at this early stage. It's a story that will need to be monitored, both for health and performance purposes, until we have an answer in one direction or the other.
Strasburg has mostly pitched well this year, with a 3.13 ERA and 118 ERA+ in his first six starts, but he's also posting career-low strikeout rates, and in a sample large enough where it merits further attention -- after 150 batters faced, you can start to trust the validity of strikeouts per plate appearance, as it has stabilized. It's not necessarily predictive, but it does put some truth to the idea that something might not be quite right, even if it's just mechanical in nature, given he's crossed that 150 plate appearance threshold.