Because they train the body to work as a complete unit by training the exact muscles used during the movement. As a result, resistance band training improves acceleration in coordinated movements related to the specific sport motion.
Whatever your current form is, use the ProPull™ to work on your acceleration from the reach back through just before the release and you will get 7-8 more feet of distance than you have now, for every 1 MPH of increased disc speed.
To get better ... ProPull™, FIELD WORK, PLAY - REPEAT .. REPEAT...
