I've been thinking that lately as well, TJ. Not sure why I just became aware of that, but that awareness really came to me in the last couple of years. There is tasty little licks all over when he didn't have to sing. I love to listen to the Jerry backing licks in Looks Like Rain and other pedestrian Bob numbers. It keeps me off the "next" button.
The other thing that's raised in my conciousness is just how sweet Bob's playing was in '76-'79. I back to some old favorite shows in my commute. I grabbed a bunch of Matrix shows with the Grateful Grabber. '77 Boston Garden & '77 Buffalo. Bob play's some stuff on the 5.9 show that is crazy-freakin' odd by rhythm guitar player standards, tonally (largely) constant, and rhythmically ...hmmm...astonishing. But this, I just realized, is a diatribe.