It's not about the direct effect of central banks but indirect effect of the speeches that they make. Even if these guys sneeze then whole crypto currency catches the cold and that is how it is working since last year December. These are the peak peeiods since when the news Fud started from the banking system. This is just because of negativity that they create though such news. The media also boosts these things in different way and thus push the panic stuff through crypto lovers and there we see the dropped prices. So yeah they do affect it.