This is from "a Bill Simmons reader," at least that's what the guy I got it from said. It must have been a comment on one of his articles.
The Nazgul were the characters in "Lord of the Rings" that were former kings who turned into demons that were constantly chasing the ring. It completely consumed them and robbed them of their humanity. I think this sums up the situation in Miami.
It's absolutely perfect. Kings who went wild in search of a "ring" to where they lost their humanity (or in this case, their legacies, competitive attitudes and identities as superstars.) I laughed really hard at this.