Maybe just a confusion due to me not being native english speaking and not fully understanding “in bounds”.
But the state machine for the ball has an “out-of-bounds” state from which it can go to various other states. And the class model specifies it to be unconditionally one in bounds of a field. So I would interpret it as when the ball is kicked out of the field it has to be deleted which is in conflict with the state model.
It may also be that I don’t understand the rules of soccer. A sport I would like to see much less of in the newspapers here in Sweden. Much much less.