Initially when I started shooting like many others my aim was to produce those crisp clear images that would have ever one go WOW! In those days it was sin to have anything blur in the Image, one aimed at freezing everything.
Then with time once one had perfected the freezing it was time to thaw... I began experimenting with motion in a new way. Rather than have a crisp image the aim was to have a certain amount of blur in the shot to highlight the movement.
A theater environment often forces you to choose a low shutter speed to get the right exposure and this usually gives you blurry images, but if you get the balance right you can get a shot that has that crispness to it and yet highlights movement.