Dragging your foot might be OK, but you got to watch yourself when you do that. If you train your body to drag your foot, then you might start doing it on your fastball which is going to slow your body down and force you to throw your fastball with all arm.
Make sure that your foot does not come off the ground until the ball is released.
you have to not dwell on scraping the foot... the scraping of the foot happens when proper hip rotation fires the drive leg over the body...
if you lead with the hips and use them, all will fall naturally
I agree, drewski...drag-line is a result of posture and mechanics, not a cause of posture and mechanics. Guys who focus on on having a certain kind of drag-line from their post-foot action are putting the cart before the horse.