"It's just to give Jarrod a couple of extra days," manager Bob Melvin said. "He was feeling it a little bit yesterday, and last night when we went home we felt like the best thing to do would be push him back a couple days and make sure he's fine."
That gives Parker, who tweaked his hamstring in Saturday's start, a full week's rest. And Straily, optioned last week at the start of a stretch when the A's didn't need a fifth starter, was expected back Saturday, anyway. So, essentially, they're simply swapping rotation spots.
Had Parker not been available for an extended period of time, however, Melvin confirmed top pitching prospect Sonny Gray would've been called on to make his big league debut.
At the time of Straily's demotion, he was 4-2 with a 5.00 ERA in 12 starts. He has a career-high three-game winning streak over his last seven starts, but has tossed fewer than five innings in each of his last two.
"I think he's done enough this year, certainly, to be that guy," Melvin said. "You don't ever want to promise a young pitcher that when they go down that they're coming back on 'X' date, because you want to make sure he has an edge about him and goes out there and competes like he normally would. He's done some good things for us this year. The last couple of starts haven't been his best, but he was on quite a roll for us there, too."
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.