Her peers from the golden age of 2010s radio diva pop also went through wobbly phases when it fizzled—see Taylor Swift’s Reputation, and Lady Gaga’s Joanne. But they quickly recovered their mojo in ways that felt true to themselves. Perry and some others—Pink, for example—not so much.

She was one of the world's biggest pop stars – but her new album has been plagued by controversy and failed singles. Here's why she's stumbled – and what it says about music today.