I think that is just his affect. I believe he is speaking off the outline and trying to have an easy going, laid back approach. Herd, Weaver and some of the other heavies do this.
These guys have a comfort level standing up before thousands of people hanging on their every word. So they just get up there and talk. They want to come across as personable, relatable, and down to earth. I don't think he's bumbling or inept...he's just a guy running his mouth in front of an adoring crowd.