"It just didn't look to me like it was his very best stuff from the very beginning," manager Bob Melvin said on Tuesday. "You can tell from the side that the ball wasn't coming out of his hand like it normally does and creating that late movement he has.
"I think he was just a little run down. He kept us in the game and got a win, but all things considered, he didn't look 100 percent right, and I had a conversation with him after the fifth and he wasn't in total disagreement that it was time for him to come out."
The A's will wait to see how Parker responds in the next couple of days and how he feels physically to determine whether he'll be able to stay on track for a start in the American League Championship Series, should Oakland advance. If rest proves to be the best route to take, Oakland has other starting options in lefties Brett Anderson and Tommy Milone, and possibly right-hander A.J. Griffin, who is on the mend from right elbow tendinitis.
Either way, Melvin is hopeful the issue with Parker proves to be nothing more than fatigue. Parker pitched at least eight innings in three of his six August starts, before struggling some in September. He finished the season at 197 innings.
"It could be a dead arm or a period where he's getting a little bit tired potentially," said Melvin. "He battled out there. Maybe not his best velocity at times, maybe the late movement he creates wasn't there, but you take him out after five, you get what you need, but maybe just not as long as you normally expect out of him."
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.