Bruno Mars has one problem: he's too polished. Music is about emotion, about an artist calling up something from deep within that he or she can't express any other way except through song (see Adele). Mars is an incredible singer who can write killer hooks to pop songs, but he lacks a certain rawness and as a result his performances always feel a little flat. What he's missing is exactly what the late Amy Winehouse once possessed, which makes his rendition of "Valerie" a song Winehouse and Mark Ronson hit out of the park in 2007 feel all the emptier. This performance is the musical equivalent of a student who knows the answers to every test question but can't explain what any of it means.