"I woke up and my elbow looked like a right triangle. It was just up and stiff," said Braden. "It's not painful. There's just no flexibility. ... I can't make 17 more starts, or however many we've got left. You can't pitch that way and I'm not doing my team a favor and I'm not doing myself any good."
Braden will receive treatment on his elbow over the next few days and could make his next start Saturday in Cleveland.
"He's had, the last couple of weeks, a little stiffness off and on," A's manager Bob Geren said. "We just think a little more rest might help it quite a bit. It's been six, seven days. He'll get a few more, so it could be about a 10-day window. That might do a lot of good."
Geren said Braden has been throwing fewer breaking balls, concentrating on the fastball and changeup. The lefty previously had an MRI on his elbow and is not scheduled for a follow-up, the manager said.
"We'd like him to get a few more days [of rest] and hopefully knock it out completely and [have him] feel good the second half," Geren said.
Braden's eight consecutive starts without a win following a perfect game ties Mark Buehrle for the longest in major league history, according to the Elias Sports Bureau.
Braden hoped to end the streak against the Orioles, against whom he is 5-1 with a 1.41 ERA in seven career appearances.
Instead, however, Geren called upon Vin Mazzaro to make the start.
The Associated Press contributed to this story.