Expecting Michael Bay to direct a movie with a coherent narrative is something akin to getting mad at a cup of yogurt for being a lousy conversationalist, but Transformers: Age of Extinction is a new low for Bay as a storyteller in that it wallows in its mediocrity. I suspect that more people than usual will leave Extinction with the vague feeling that the ticket price turned out to be kind of a rip-off in that genial American snake-oil salesman tradition because it's quite possible that, after four movies totaling over ten hours, Michael Bay has finally exhausted his seemingly boundless enthusiasm for this concept.