Rehabbing righthander Chris Carpenter threw only 30 or so pitches in the bullpen during a Wednesday afternoon session after tossing twice that number Monday. But this was by design, said Carpenter. “It was almost like a pre-game warmup,” said Carpenter. The plan now calls for Carpenter to take two days off and throw an extended session Saturday. On that day he plans to sit down three times during the session, to simulate a changing of sides. Carpenter said that the process would be extended to have him sit down four times by the time the team returns home from an eight-game trip on May 28. “Then,” said Carpenter, “we’re going to know where we go.” By appearances, Carpenter is conditioning himself to be a starter. Carpenter had a baseball field for youths named for him at Jackson Park in Berkeley on Wednesday morning as part of the Cardinals Care program.