It's simple. Makes sense when it's not expected to and doesn't make sense to keep you wondering. This is the second time I read it, the first when I flicked someone else's. Well, now I have my own :)
True to Tim Burton's fashion, Oyster Boy and other stories is indeed... melancholic. It explores the dark side of childhood, only adults will hang their head in shame... because the truth portrayed in Burton's short stories, strikes a chord. At least once in their life, they must have mistreated someone just because he or she doesn't conform to what they think 'normal' is. And it breaks hearts.
Read it, borrow it.