Time Keeping

In a post of Kyle Gann's, one of his regular commenters, a composer, says:

There is also the problem with timing. I once formed an ensemble with classical, jazz and rock musicians: the classical musicians were slightly behind the beat, the jazz musicians slightly ahead, and the rock musicians dead centre, almost like a computer sequencer. This is changing now, I did a session with classical string players a few years ago who were as dead on the beat as any rock player.