Use a deadzone for very used, old controllers which aren't percise anymore

stick-deadzone

// http://www.third-helix.com/2013/04/12/doing-thumbstick-dead-zones-right.html

float deadzone = 0.25f;
    Vector2 stickInput = new Vector2(Input.GetAxis(“Horizontal”), Input.GetAxis(“Vertical”));
    if(stickInput.magnitude < deadzone)
        stickInput = Vector2.zero;
    else
        stickInput = stickInput.normalized * ((stickInput.magnitude - deadzone) / (1 - deadzone));