Weepiper's description was: "...whoever it was had broken it all into little pieces and spread it over a good eight-foot square area (there was even some inside the door)." A deliberate act, in other words, not just the throwing and smashing of a bottle against a door, which would have resulted in larger shards, and would probably have left the neck of the bottle whole or nearly whole. Also, if it had been thrown, more of the bottle would probably have made its way inside the cat-door.