The former Cy Young Award winner has experienced a setback in his rehabilitation from surgery to repair a nerve problem in his throwing shoulder and is "very unlikely" to pitch in 2013, Mozeliak said.
The 37-year-old is reported to be considering retirement, after missing most of last season with the ailment. He returned at the end of the season to make three starts as well as three more in the playoffs.
Although Carpenter hasn't yet made a decision on whether to continue, "at some point, he'll start reflecting on the next chapter of his life," Mozeliak said.
The right-hander earned the Cy Young award in 2005 and was Comeback Player of the Year in 2009 after battling elbow problems.
Carpenter played key roles in the Cardinals' World Series titles in 2006 and 2011. He sports a 144-94 overall record and a career 3.76 ERA over 15 seasons with the Cardinals and Toronto Blue Jays.