The best Major League hitters make contact on the plane of the pitch. There is too much consistent proof to think anything else. The pitch plane and swing plane meet pretty much head on when a fastball is thrown. Hitting the ball while the bat is moving downward would be a mistake. To hit a ball well on a downward path, would mean a hitters timing and accuracy would both have to be absolutely perfect.
Anyone with any doubts should order Rightview Pro and see the major league hitters for themselves.