She hasn't "lost" her digital power; she's just been stumbling lately. Maybe it's over-saturation. Maybe her songs sound very similar to each other on the radio when released in such a short span of time? To the common listener, having Roar, Dark Horse, Birthday, and This Is How We Do on the radio simultaneously can be confusing and overwhelming.
I'm also very partial to theories of the parallels between the PRISM era and Gaga's Born This Way era...