NEW YORK -- The A's activated right-handed pitcher Ryan Cook from the disabled list Tuesday, making room for him by putting right fielder Josh Reddick on the DL.
Reddick suffered hyperextension of his right knee in a collision with the right field wall Saturday, took Sunday off and the A's determined that he'd need more time to be ready.
"He won't do any baseball work until we get home,'' manager Bob Melvin said of Reddick. The manager said Reddick had an MRI and no structural damage was in evidence.
Cook has spent most of the season on the disabled list, missing all of spring training with a right shoulder strain. He came back a week into the season and pitched in short relief from April 7-May 7 until his forearm started acting up.
He threw one inning with Class-A Stockton Saturday, after which he said his right arm "feels great, ready to go.''
Melvin said he'd work Cook, who made the 2012 All-Star team as a closer, in some lower pressure situations just to get him pack into the routine.
"The problem is every time you say that, you wind up needing to pitch in extra innings with the bases loaded,'' Melvin said with a wry smile. "But we'll try to ease him in.''
He'd missed two games with a strained calf, and it was the desire on Melvin's part to make sure the injury doesn't linger that kept Moss from playing first base, a job that went to Alberto Callaspo.
"I'm not 100 percent sure (Moss) couldn't have played in the field somewhere,'' Melvin said. "He feels a lot better today.
"As important as he is to us, we want to see how he reacts to some at-bats and actually getting out of the box and running down the line, which is the most difficult thing with those kinds of injuries.''
The 29-year-old Sizemore was hitting .265 for Triple-A Scranton, and he's expected to face left-handed starting pitching. The A's started lefty Scott Kazmir Tuesday and have another ready to go in Drew Pomeranz on Thursday.