Melvin said Doubront, who suffered a right foot contusion in his last start, is "probably good enough to pitch, but there's still a little bit of a noticeable limp."
"In a National League park, where you have to hit, run down the line, the whole bit," Melvin said, "we just felt like an extra two days would benefit for him."
Brooks joins the A's for a second time this season, after going 1-1 with a 6.19 ERA in four games (three starts) in his first stint. He was optioned Aug. 15 and went 1-0 with a 2.25 ERA in two starts for Nashville. He has never faced Arizona in his career.
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.