"Had [the inflammation] happened now, maybe I'm not back in time," said Cook, who posted a 2.54 ERA in 71 appearances last year. "Now I have time to get back and should be ready to go in just a couple weeks.
"I don't feel any pain right now. Today I actually felt better than I have in a really long time. I feel great. It's night and day. In fact, I ask myself, 'How long was I dealing with it without knowing?' My arm felt alive, and I haven't really felt that out of my hand in awhile."
The right-hander was already throwing from 120 feet when he first experienced discomfort, so it's not like he's starting from scratch. He'll be a few weeks behind other pitchers, but is fully expected to be Opening Day-ready. The A's never even sent him for an MRI.
"They didn't think it was necessary, and neither did I," Cook said, "so it was nothing that was ever a scare. Just enough that we wanted to shut it down and get it right before we got going."
Jane Lee is a reporter for MLB.com. Read her blog, Major Lee-ague, and follow her on Twitter @JaneMLB. This story was not subject to the approval of Major League Baseball or its clubs.