The ornamental design for a ballrack, as shown and described.
FIG. 1 is a top, front, and left side perspective view of a ball rack
showing my new design;
FIG. 2 is a top plan view thereof;
FIG. 3 is a front elevational view thereof;
FIG. 4 is a right side elevational view thereof; and
FIG. 5 is a top, front, and left side perspective view thereof, the
broken-line depiction of a number of balls being for illustrative purposes
only and forming no part of the claimed design.