The fact you don't know much about the prize is possibly their best bid for legitimacy. I heard some mainstream radio and commentators questioning the point of the award because "no-one cares". What they actually meant was, "no-one's paying us to attend a flashy, hyped up back slapping session and we don't like it".
To prove the point, you question their previous choice of PJ Harvey's most mainstream album. But to me, her "most mainstream" is still nothing that was marketed or released against, say, Coldplay or Madonna.
I don't know much about them, but long may they exist.