It's all about the call and response, with Joe trying to cop Warren's feel rather than do his own thing...a trap of sorts that old, experienced cats pull on younger hotshots (I've been a victim myself). Warren pulls out some crazy phrasing and Joe can't cop the feel...and he knows it...you can tell by his body language from around 7:27-7:35...and then he starts doing his own thing again.
You hang out in enough blues clubs and see enough blues jams, you become familiar with how the older, wiser cats cut heads...they bait you and then make you look stupid. Les Paul was notorious for doing this to hotshots who sat in with him (Slash told a story of Les absolutely taking him to school and basically humiliating him when he sat in). It has nothing to do with chops (no doubt Joe can outshred Warren), its all about phrasing and feel...like him or not, few players can touch Warren at that game.
I didn't expect too many people here to get it as I don't see many guys steeped in blues, but I expected you to get it Carl...still kinda shocked that you didn't. A very different kind of ass-whooping than the beating Zakk took.
Here's where the blues-tards try to argue...go for it