WASHINGTON -- Stephen Strasburg added a new slider to his repertoire this past season, and while the pitch was devastatingly effective, it may have led to the elbow injury that ended the Nationals right-hander's season prematurely and forced him to miss the postseason.
Strasburg, who left the mound on Sept. 7 with what would later be diagnosed as a slight tear in his right pronator tendon and weakness in his flexor mass, believes the issue developed during the season in part because he became too reliant on the slider. After it was virtually not used at all previously, the slider became Strasburg's second-most-used pitch in 2016 (behind his fastball). He threw it 17.1 percent of the time, because he was able to get hitters out quickly with it.
"I fell in love with it," Strasburg said at Nationals WinterFest on Sunday. "Because it was working, especially the first half.
"My arm just wasn't accustomed to throwing that pitch that many times. I was throwing it significantly more, even when I didn't have it."
In the first half, Strasburg said he had no problems repeating his delivery to throw the slider, but that became an issue as the season progressed. He guessed it was due to fatigue, and eventually it began aggravating his forearm, which led to the injury.
The slider had become such an effective weapon, particularly against left-handers. Strasburg held lefties to a .615 OPS in 2016, well below his career mark of .635 against lefties. Opposing hitters had a 12 percent swing-and-miss rate overall on his slider. Strasburg reiterated that he will not eliminate the slider completely, but rather try to use it more efficiently and mix in his other pitches as well, especially his changeup.
The Nationals have also said they will adjust the way they handle Strasburg in 2017 in an effort to keep him healthy for a full season. Pitching coach Mike Maddux hinted that perhaps the club will modify his throwing program in between starts to maximize his effectiveness at the end of the season.
"We're going to sit down with him and discuss it," general manager Mike Rizzo said. "He was here early before the WinterFest to go over it with all our medical people. First of all, we checked him out. Second of all, [we collaborated] with our strength and conditioning guys on how we're going to handle him this offseason in preparation for Spring Training. And then through Spring Training, we'll devise a workout program to handle the forearm soreness."
For now Strasburg is enjoying a normal offseason and will begin his throwing program in January, as he usually does. He was working toward a comeback during the National League Division Series, even progressing to the point of throwing bullpen sessions. However, the Nats could not advance past the Dodgers and he had to watch another postseason from the sidelines, a feeling he described as helpless.
"I was frustrated at the end of the year not to be there with the guys," Strasburg said. "That's kind of my big motivation going into this year. Just because you sign an extension, that doesn't mean the work's all done.
"There's another hopefully seven years with this team, and I want to be there. I don't want to miss any more time."
Jamal Collier covers the Nationals for MLB.com. Follow him on Twitter at @jamalcollier. This story was not subject to the approval of Major League Baseball or its clubs.