The quantum locked, dont even blink or youre dead creatures somehow get to Trenzalore, past the shield fine. But when one grabs Clara she just gets stuck, no sending back in time, no killing, breaking ankles, nothing. They then fail to appear in the rest of the episode. This on top of the Statue of Liberty moving in The Angels Take Manhattan, which really deserves a whole section in itself. Really, not one person, bird or animal was looking at that statue? Its another example of Steven Moffat messing up his own monsters. Blink was fabulous, as were the Bizantium episodes, but any other appearance since has been a let-down. Theyre supposed to be quicker than you can imagine and would get you as soon as you blink but they have been overused and watered down.