Ball was from the deep south. I see it in how he reacts to the music and the grove while he's watching Nat solo. Plus, I think that "Work Song" is a variation of the old, almost obsolete, eight bar blues. Man, you could get some real soulful milage out of the eight bar blues. So "Work Song" is a sixteen bar blues, which would seem to me to be a variation of the eight bar form. The tune they play as a tag to close this show seems to have a sixteen bar outside with a little eight bar bridge turnback. Like a little variation of "Unit 7", but different. The blues, with a kind of southern vibe to it. Just beautiful.
I used to see this band when they played at a little art gallery near my town. And I checked them out in "65 or '66 when he had Charles LLoyd playing tenor. They were incredible!