The ornamental design for a baseballtrainingplate, as shown and described.
FIG. 1 is a top perspective view of a baseball training plate showing my new design;
FIG. 2 is a right side view of the baseball training plate, (the left side view being a mirror image thereof;
FIG. 3 is a front view of the baseball training plate;
FIG. 4 is a rear view of the baseball training plate;
FIG. 5 is a top view of the baseball training plate;
FIG. 6 is a bottom view of the baseball training plate; and,
FIG. 7 is a reduced scale top view of the baseball training plate, wherein the broken lines shown beside the training plate are included for the purpose of illustrating environmental structure that forms no part of the claimed design.