"It's something we have to do for his health and wellbeing," manager Matt Williams said. "We have to make sure that we get him well as quickly as possible. He certainly will not make his next turn for sure."
This marks the second time Strasburg has been placed on the disabled list this season. His first stint, which began May 30, was due to neck muscle tightness. Strasburg missed almost a month of action while he was trying to fix his mechanics.
It appears to be a different story this time. Strasburg hurt the oblique Saturday against the Giants. He had cruised for 3 2/3 innings, allowing one hit and striking out three batters.
After inducing a groundout from Buster Posey for the second out of the fourth inning, Strasburg grabbed at his left side, and Williams, pitching coach Steve McCatty and assistant athletic trainer Steve Gober went to the mound.
Strasburg tried to talk Williams into letting him stay for another inning, but he was ultimately removed from the game.
"It is what it is and he is disappointed about it and so are we," Williams said. "It's part of the game. We have to get him back healthy and going as quickly as we can. We want to make sure that he is 100 percent, fully ready to go when he does come back."
It marked the third time Strasburg had to leave a game this season because of an injury. He previously had problems with his back and neck.
"Since that was going to be the case, I iced it a couple of times," Strasburg said Saturday. "I really don't have an explanation [for the injury]. Everything felt good. I threw a pitch to Posey, he grounded out, and I felt the grab [in my side]."
Strasburg had pitched well since coming off the disabled list June 23, allowing two runs over 15 2/3 innings.
As for Jordan, he will likely be the long man out of the bullpen, while Tanner Roark could return to the rotation. After Strasburg left the game Saturday, Roark entered in relief and allowed two runs in 4 1/3 innings.
The Nationals have a day off Thursday and the team could go with a four-man rotation before the All-Star break.
"We can adjust if need be, depending on where we are at and we'll go from there," Williams said. "Right now, all we know is the Reds series. We'll adjust accordingly from then on until the All-Star break."
Jordan joins the Nationals for the third time this season. The right-hander was last recalled from Triple-A on May 24 and appeared in two games (one start) before returning to Syracuse on June 4.