The Padres placed McCoy on the 10-day injured list Sunday with back inflammation.
McCoy's IL stint is backdated to Thursday, making him eligible to return for the Padres' final game of the regular season Sept. 29. He has appeared in 19 games with the Padres this season, slashing .204/.278/.245. The Padres will replace McCoy on the 28-man active roster with veteran infielder Nick Ahmed, who was called up in a corresponding transaction.