The right-handed pitcher threw a live batting-practice session Friday in Kansas City, and he was expected to complete a second session Monday afternoon before the Cardinals opened a three-game set with the Marlins at Marlins Park. That plan was shelved Monday when Carpenter didn't respond the way the team expected from his first session.
"He just didn't feel strong, so we're waiting until we get back home," manager Mike Matheny said. "There isn't a big rush. ... We've been doing that from Day 1 -- seeing how it feels each time before jumping right into another live session. Take a little more time and get back home."
Following their three-game series in Miami, the Cardinals have an off-day Thursday and then return home Friday. At that time, the team will decide when the next step in the rehab process will take place for Carpenter, who has been on the disabled list since March 26.
His BP session in Kansas City marked the first time Carpenter faced live hitters since March 18, during Spring Training. It was after that session that the team shut down the righty due to a nerve issue that limited the strength in his throwing shoulder.
Prior to Monday's revelation, Carpenter had not experienced any setbacks since resuming a throwing program earlier this month. After Friday's session, Carpenter emphasized that his strength felt like it did prior to the injury, and that the rehab process was focused on his endurance and refining his pitches.
It is unclear if Carpenter will be able to pick up where he left off following his first session against live hitters when the team decides to take the next step with him.
"That's the whole thing about this, we really don't have anything to go off of," Matheny said. "There really isn't any history anywhere to tell us where he should be and what he should do, how much time he should take in between [throwing]. ... That's why we've been so careful with him.
"We're very careful not to put a level of expectation on what he has to do, where he has to meet this deadline. We just keep moving forward."