It really is more of a C box--since it is a closed position--I it sounds to me like he used the closed position a lot for leads and such--I was listening to Corrina Blues, and there is a little lead figure that he repeats--he may use an open chord position, but that little figure just pops out in the closed position, and it is awkward in the open position--I am not sure if he is unorthodox or not--he does do a lot of stuff that people don't do now, but we don't really know much about the way the guys who he listened to played--

You've ruined me for the day, I am afraid, because I have the guitar out, and I am fooling around when I should be working--