If you are quick and have a good eye, there isn't any need to duck, I find that it is difficult to control where the bat goes (I.e. periscope). Dodging is my way of avoidance and at the last moment, once I am sure I am not going to try and hit it, during the indoor nets one of the quicks clipped the edge of the mat and I watched it fly past my grill ! It was a bit like the matrix, because I never stopped looking at the ball I knew where it was.
There have been previous posts on this, get someone to throw down fast tennis balls at you but do it in full kit.
Maybe a need of another post, but how many people are prepared to watch the ball hit their grill and try and ride it like a boxer would a punch?
The reason I ask is if you naturally lift your head up to dodge, you open up your jaw to the rising ball, if you rotate your head, yes it will hurt but it is more of a glancing impact and on the grill not your face?