Deadzone denotes the amount you can move your joystick/controller stick before the craft will begin moving in that direction. So the larger I set deadzone, the more I have to push the stick down to get the craft to pitch "down". This ensures small/accidental signals don't get sent to the fighter and thus the fighter becomes difficult to control, requiring too many little adjustments from your accidental joystick movements. Set the deadzone too large though and it becomes difficult to control the craft because too little of the spectrum of joystick movement translates into craft movement. You thus end up with only the ability to denote large craft movement or the joystick's delta between small and large craft movement very small - similar to setting sensitivity too high and deadband too low but where the joystick delta is all near the stick's periphery rather than the center.