Glad you liked it! :D
The reason is basically a fix to something, my brother play-tested the game and found out that vibrating the mouse ever so slightly while holding the ball in hand to a ball in the air would generate huge scores, so I gave the balls immunity for a couple hundred milliseconds after being thrown by the player or the ball npcs.
Also, the cursor position marks the center of the hand hitbox, the fingers don't really do anything, the animations are just smoke and mirrors