Downs, who hasn't had shoulder issues since labrum surgery as a college freshman in 1995, isn't sure how long he'll be out or what the initial rehab plans will consist of.
"I'm hoping it's a two-week deal, but we'll see," Downs said. "We'll do what we can, as usual, to get back as fast as we can."
"I think we're comfortable with the fact that it's not going to be anything that's going to push him back too far, but it's probably something that's going to need a couple of weeks to settle down," Angels manager Mike Scioscia added. "We're going to take it one step at a time. Right now it's a very minor issue and we want to keep it that way."
Downs has been one of the most consistent Angels relievers all year -- and last year, too -- but has struggled a bit recently. He gave up just one run in 30 innings in the first half, but has surrendered nine of them, on nine hits and six walks, in five innings since the All-Star break.
The 36-year-old lefty, who has dodged two prior trips to the DL this season, doesn't believe his current injury had anything to do with his recent struggles.
"There's no excuses for what happened the last couple of weeks," he said. "It's baseball."
Without Downs, their crucial lefty complement to righty Ernesto Frieri in the late innings, the Angels suddenly need guys such as right-handers Kevin Jepsen, LaTroy Hawkins and Jason Isringhausen to play bigger roles, especially since no reliever was added before the non-waiver Trade Deadline.
Frieri (.494 OPS) and Hawkins (.453) have been good against opposing lefty hitters; Isringhausen (.714) and Jepsen (.708) have not. Takahashi, with a 4.37 ERA in 35 innings, is expected to remain in more of a long-relief role.
"We'll lose matching up later in the games, turning a guy around, neutralizing power," Scioscia said. "There's a lot of things that Scott brought from a left-handed perspective that we might not be able to do. But there's no doubt the arms we have are good and hopefully are going to hold leads as good as we've been."