Leigh
I think your traction explaination makes curve balls go the wrong way. If
viewed from the Goodyear (or Fuji) blimp a right handed pitcher throws a ball
with a counterclockwise spin, which breaks away from a right handed batter.
Doesn't the traction model work for curling? I'd expect the leading edge to
bite into the ice while the trailing edge rides on a film of water.