Double-A Chattanooga placed McLain on its 7-day injured list Sunday due to an unspecified injury.
The Reds haven't provided an explanation behind McLain's placement on the IL, but he hadn't played in either of Chattanooga's past two games after apparently getting hurt Thursday against Tennessee. For the season, the 22-year-old infielder is hitting .233 with 12 home runs and a 16-for-17 success rate on stolen-base attempts across 261 plate appearances at Double-A.