It's not like Rihanna hasn't flopped with a single before. It's more that Kanye has obviously taken control of her music and Jay Z has taken control of how it is released. They have turned Rihanna her era (and with it her career) into a huge mess, and she appears powerless to stop it. That's why the Navy have lost their cool. Just when they thought Rihanna had taken the reins, the horse is actually dragging her through the dirt.
