I may be way off base here?the batters box, I think is 36 inches from the back corner of home plate rearward and 48 inches forward or 84 inches front to back. I guess it may vary ASA, NSA, state to state high school rules etc. At 40 feet I would guess the release point to be 34 to 35 feet for most pitchers. Now at 43 feet it may be 37 to 38 feet.
I see high school and select coaches? mandate for the hitter to stand at the front edge of the batters box at 40 feet now, if there is even one marked out legally. This speeds up the ball and lessens the hitter?s ability to recognize the speed and spin of the pitch. A pitcher that has a good change up and a faster pitch usually makes those hitters look ugly. I can hear some of you saying catch it before it breaks or drops or rises. None of the quality coaches I know believe that theory. Look at the college, Elite World Teams and NPF hitters and they adjust according to who is pitching and what their speed and best pitch is?well not all college teams maybe. This is why we teach our hitters to move in the box during the pitchers motion, so she will have to make choices also.
The pitchers job is to upset the hitter?s rhythm and timing and to make the hitter and the umpire make choices. The great pitchers and hitters know how to make those adjustments. Look at your World Cup games?good hitter?s and pitchers have made those adjustments and we will also to 43 feet. It is not that big a thing.