The Cardinals placed Carpenter on the 10-day injured list Monday with a lower-back strain.
Outfielder Jordan Walker was recalled from Triple-A Memphis to take Carpenter's spot on the 26-man active roster. Carpenter had played in just one of the Cardinals' first 10 games of August, though his lack of usage might have had more to do with his standing as a reserve designated hitter rather than because of the injury. Carpenter had served as a strong-side platoon option at DH for a brief spell from mid-June to early July, but his playing time had fallen by the wayside since outfielder Lars Nootbaar returned from the injured list, which bumped Alec Burleson back to DH.