Hi all,
I think I am not the only piper to have problems with my left ring finger. Apart from being less controllable than the rest, when doing a pat on the A (as with an A roll) my fourth (ring) finger often misses the tone hole partially. This results in a muddy or almost inaudible pat. I have a very straight finger posture (this is nature-given, I also play piano that way). Moreover, my fingers are quite long and skinny. I found the only remedy is to push my left wrist forward, which results in bending it at an almost 90 degree inwards. Not a very relaxed position and difficult to maintain when playing for a longer period. I wonder if any one of you has similar problems. What do you do to get a clear, crisp A pat (apart from practising your a.. off)?
Christian, your forearms and wrists should form a semi-circle in front of you. They should be soft and relaxed. So should your fingers. Try lightening up on your grip, as well.
Oh, look! I have no a..! 
djm