One trick? Maybe, BUT WHAT A TRICK. All I know is when I have seen B.B. three times. He played lots of different licks to lots of different tempos.

What he and Muddy did (more Muddy than B.B.), with some others invented a sound that lasted for generations. And they both put on a heck of show well into their old age.

Robert Johnson was not much of a player. But I hope he has earned y'alls respect!