[greymule]

In ASA, any pitch that hits the plate HAS to be a ball. It didn't pass through the strike zone. However, many leagues play with a mat that fits behind the plate, and in that case the strike zone is purely on the ground: any ball that hits the plate or the mat is a strike. No doubt various places around the country play with modifications to these rules, though.

In mat ball, many pitches that would be strikes in regular ASA are balls, and vice versa. For example, a 12-foot pitch that hits the back of the mat is a strike, but in regular ASA that pitch would be a ball to any human-sized batter. Conversely, a 6-foot pitch might pass directly through the regular zone but hit behind the mat for a ball or catch the outside corner but then miss the mat). Leagues use the mat to reduce arguments over balls and strikes, and with today's rock-hard balls and juiced-up bats, it doesn't really matter.

Incidentally, the strike zone is AT THE PLATE. It is not determined by where the batter is standing in the box. That distinction is crucial, much more important in slow pitch than in fast pitch or baseball. It is also the front knee to the back shoulder.