the only reason you'd trade Humph would be in a package deal where you include picks and rookie contract players like Sully for a major upgrade (Love, Melo, etc). Those kind of trades don't seem like they are on the table. Makes more sense just to let Humph expire.
Bass is not that desirable and he also expires prior to 2015 so there is less urgency to dump him right now.
You're hearing about Green, because he's a mediocre player making big money through 2016, but presumably might net us an expiring contract. You're hearing about Rondo, because he's available and still a fringe star in this league that could command assets.