Watching him sing "Nothin" and even "Black Country Woman" since it was a bit heavier, on the Raising Sand tour was a good example of him proving he's still a rock singer. Not that he needs to prove anything to anyone. He seems to be able to do it when he wants. But to sing that way for an entire tour at 60 years old, when so much is expected of you is another thing. His voice wasn't perfect live for an entire tour in his 20's either. Why strain his voice when he doesn't have to?