How?
On first connection of a controller, a screen to calibrate the best values for deadzones should be available, where the user does not touch the joysticks whatsoever for a certain period of time, then pick a rounded number for deadzone values.

Why?
When a user first connects a controller, and the deadzones require to be higher than the default 0.2, then inputs will be continually be registered and the user will not be able to use Minecraft. This is present even when they decide to just use keyboard and mouse, because the constant input will override keyboard and mouse mode back to controller.