Cook said he hoped to be activated for Monday's contest at Minnesota, but on Sunday morning manager Bob Melvin said he did not have his mind made up.
"We'll activate him on the road trip at some point in time," Melvin said. "Which day, I'm not sure."
The plan was for Cook to get in two innings of work with Stockton, but he was able to record only two outs while allowing two earned runs on two hits with two walks and two strikeouts. Still, the valuable right-handed setup man said he was happy with the way his arm felt, despite the subpar results.
"I came out of there feeling like I'm ready to go," Cook said. "Arm feels healthy, I feel healthy. Got that one out of the system hopefully and now it's time to go, as far as I know."
Cook said his past two Minor League appearances last week with Stockton had given him confidence that he was ready to return to duty, saying Thursday's outing served as something of a turning point. The 26-year-old has made 71 appearances for the A's in each of the past two seasons, compiling a 2.30 ERA, 1.11 WHIP and 9.4 K/9 ratio in that span. Clearly, he is champing at the bit to get back on the big league mound.
Meanwhile, Cook also got to watch outfielder Craig Gentry play in his first game of a multicontest rehab assignment as he tries to come back from a balky back. Gentry, who is expected to take over a reserve outfielder role in Oakland when healthy, went 2-for-4 with a double while playing all nine innings in left field for Stockton on Saturday.
"He looks good," Cook said.
Melvin said the plan was to have Gentry play one or two more Minor League rehab games before the manager would make a decision on his return.
"We'll have some tough [roster] moves coming up on both ends of it," Melvin said, referring to the outfield and bullpen.
Alex Espinoza is a contributor to MLB.com. This story was not subject to the approval of Major League Baseball or its clubs.