The ornamental design for a baseballbat, as shown and described.
FIG. 1 is a front plan view of a baseball bat showing the new design;
FIG. 2 is a back plan view thereof;
FIG. 3 is a bottom plan view thereof; and,
FIG. 4 is a top plan view thereof.
The broken lines, if any, shown in the drawings are shown for illustrative purposes only and form no part of the claimed design. In addition, the surface shading, if any, illustrated in the drawings is provided merely to highlight the contour of the design; it is not intended to be illustrative of texture or gloss.