Cook injured his knee when he was spiked in a collision at the plate in his Red Sox debut May 5.
"He still has the stitches in there, but he's kept his arm in good shape," manager Bobby Valentine said. "We're trying to simulate some throwing, so he throws and sits down and throws and sits down, so when it is time for him to pitch again, he doesn't have to start from the two-inning stint. He might be able to throw five innings and have his arm built up to that 70-75 pitch barrier."
The right-hander is eligible to return from the 15-day disabled list May 21, when the Red Sox open a three-game series at Baltimore. The club was unsure if Cook would pitch a simulated game or make a rehab start in the Minors before returning.
"I have no idea. I mean, I have an idea, but it's still hypothetical," Valentine said.
Cook allowed six earned runs on eight hits in 2 2/3 innings in his only start with the Red Sox. He didn't have a defined role on the pitching staff and was filling in for Josh Beckett, who missed one start with lat stiffness.