Ventura, who was sent down to Triple-A in the corresponding move Tuesday amid season-long struggles, returned to the Majors. The Royals' Opening Day starter is 4-7 with a 5.19 ERA this year.
After throwing a 2-1 pitch to third baseman Brent Morel with one out in the second inning Tuesday, Vargas grimaced and his left arm seemed to go limp.
Vargas said he didn't feel a pop in the elbow, just pain that prevented him from throwing any more.
"It didn't feel good," Vargas said.