I don't really understand his role in late night television, either. I'm with Coco, damnit. I don't consider his jokes and bits to be very "tight." It's the circle of life. His role depends on how many hunters are watching.
In all seriousness, though, his rolls aren't that hard to dodge once you get the hang of them. I'd say there's several different forms of the roll. He definitely can control what direction he's going in, possibly just at the specific point where the hunter was at the time he began the attack, but if he overshoots it he'll end up having to go around in a circle of which I'm not gonna bother trying to determine the radius.
In area 6, when he digs and goes up on the ledge, he has a set pattern that he rolls in. I believe there's two variations, based on which path the hunter he's targeting is closest to.
We've got to **** in stuff more often! - Donald Glover