"We're not going to push him to three at this point, regardless of the pitch count," Williams said. "Right now it's just a matter of arm strength and getting everybody going. Once we get to four or five innings and arms start to get tired, then we'll get a better evaluation."
Strasburg has been tinkering with adding a slider to his repertoire. He believes the pitch will help him throw inside to left-handed hitters.
The 25-year-old right-hander, who went 8-9 with a 3.00 ERA last season, has previously relied primarily on a fastball, curve and changeup.
Jim Hawkins is a contributor to MLB.com. This story was not subject to the approval of Major League Baseball or its clubs.