The bone position is the origin for scaling and rotation. You can move the ball so it's centered on the root bone. One way to do that is to click the ball, then set the world X and Y to 0,0.
Or you could leave the ball where it is and move the root bone. To do that, click
Images in the toolbar to turn on "attachment compensation". Then you can move the root bone, but the ball won't move. Be sure to turn it off afterward.
Or you could create a new bone and move the ball to be attached to that bone, instead of the root.