"These are tough things for me to address," said D-backs manager Torey Lovullo. "It's really unfortunate. Shelby's been throwing the ball extremely well. Numbers aside, you just hate to have something like his pop up. We're going to be optimistic."
Miller says he has never experienced this type of issue before, but a forearm injury sometimes is a precursor to elbow problems and ultimately Tommy John (ligament-replacement) surgery.
"Personally, I feel like I'll probably feel better tomorrow," Miller said. "I don't think it's that big of an issue. I think it's more just one of those things that flare up when you're out there.