The Grammys tend to have some tropes that dictate how they act with the major awards. Sometimes the biggest album of the year wins out - think, Daft Punk a few years ago. Sometimes the respected legend wins with a popular yet mediocre (or worse) album - think, U2 in 2006. Or a respected legend wins after death - think, Ray Charles 2005. Then you have those "credibility" reset wins where a surprise happens from an indie or semi popular artist that has been deemed "perhaps the next big thing" - think, Arcade Fire beating out Lady Gaga/Eminem/Katy Perry.
Outside of the major categories, the Grammys loves to give awards to vets/legends. Even if the album isn't good. In Nas' case he's a vet/legend but the album is actually good. I want to say he's a lock for rap AOTY but never doubt the power of Roc Nation (Jay Electronica). It's gonna be one of those two albums...I'll take a month ban if the other noms win that shyt. I think at this point, given the way King's Disease was received...there are a lot of people on that committee who want Nas to win. Swizz, Timbo, Alicia Keys, Puff...maybe even Hov.