If you listen to Jamerson's stuff isolated, it is not always pretty. We are, by now, used to playing to the grid. I have recently put a track together using a prerecorded drum track. It is very odd. The drum track is played live and bubbles along very nicely. I played the rest of the instruments using the drum track as a guide. Soloed, the bass sounds horrific - what we "know" as timing is deeply offended by what I played. But along with the drums it is just fine and dandy.