The Tribe recalled left-hander Nick Hagadone to fill Perez's spot in the bullpen.
Through eight appearances this season, Perez struggled to find the strike zone and feature the same velocity he has shown in the past with his fastball, slider and changeup. The 29-year-old missed time during Spring Training due to soreness in his left shoulder, but made the Opening Day bullpen after logging just five Cactus League innings late in camp.
"It's a different spot [than the shoulder soreness]," said Indians manager Manny Acta, referring to the source of the injury. "We were concerned because we saw his lack of velocity, but we kept coming to him and asking him about how he felt and he said he was fine. He felt that it was probably just a lack of Spring Training."
This season, Perez has averaged 82.3 mph with his slider (the pitch he throws most often) and 87.7 mph with his fastball, according to PitchFX data. The slider stood at 85.7 mph in 2011 and 86.6 mph in 2010. Perez averaged 89.3 with his fastball last season and 90.7 mph in 2010.
On the year, Perez has also thrown just 55 percent of his pitches for strikes compared to a 65 percent rate for his career. In his most recent outing against the Royals on Wednesday, the lefty issued two walks in one inning, registering only four strikes among the 16 pitches he threw.
Perez complained of soreness following that outing.
Perez, who has never previously been on the disabled list in his seven big league seasons, has posted a 3.52 ERA in eight outings, compiling four strikeouts against four walks in 7 2/3 innings. He will be eligible to be activated from the 15-day disabled list on May 11.
Indians head athletic trainer Lonnie Soloff indicated that Perez will likely need three to six weeks to recover from the injury. Surgery is not being considered.
"They don't think it's actually as bad as they've seen some in the past," Acta said. "The doctors feel that he should be able to recover, no problem."