When Otto Kemp got a knock on his hotel door at 11 p.m. on Friday night, he opened it to find a trio of Lehigh Valley coaches on the other side.

To take Kimbrel’s place on the roster, the Braves called up pitcher Austin Cox. In 19 relief outings for two Triple-A teams (the Omaha Storm Chasers and the Stripers), the left-hander had a 2-1 record ...