The Indians feel the strained muscle, which first bothered Borowski midway through Spring Training, was responsible for the closer's drastic dip in velocity and the ensuing ineffectiveness that came in his two blown saves against the Angels and Red Sox in early April.
Borowski said his arm felt great Thursday.
"A huge difference," he said. "I could see my arm speed, compared with the way it was before, was decidedly better."
Borowski will most likely throw four bullpen sessions in total. His next one is Saturday, and he'll continue to throw one every other day from there. The next step would be a simulated game, followed by what is expected to be a short rehab assignment in the Minors and, finally, reinstatement to the Tribe roster and his closing spot. So his return could come in about two weeks.
"Hopefully [Thursday's bullpen] was a significant step," manager Eric Wedge.
In the meantime, Rafael Betancourt has handled the closer's job well, saving four of five opportunities. Betancourt had a rough homestand last week, blowing a save against the Mariners on Thursday and giving up a ninth-inning homer Sunday against the Royals. But he recovered to save the first two games of this Yankees series.
"I like the way he's bounced back," Wedge said. "He's been back to his old self the last couple outings, which has been good to see."
Wedge, though, has made it clear that Borowski will resume his closing duties when he returns.
Anthony Castrovince is a reporter for MLB.com. This story was not subject to the approval of Major League Baseball or its clubs.