How about asking those mathematicians of yours to include..
Increased time of flight for the ball to travel towards the hitter and how much farther away from the point of contact the pitcher could be while backing up before the ball is hit.
My guess? Would be..with three extra feet of distance for the pitched ball to travel, the pitcher should be able to back up around 2 more feet. That’s a five foot increase in reaction time before the ball is hit..then there is the extra three feet the ball needs to travel back towards the pitcher before he needs field it..
Being conservative and not including the extra distance the struck ball has to travel back towards the pitcher, it appears as though the pitcher reaction time would be at minimum 10% higher (5 extra feet from an original 50 foot rubber) thats conservative taking into account the ball must travel a minimum of 12% further pitching from 53 feet before at pitcher can be hit.
Your math doesn’t seem to take into account defensive back up time to get set and extra reaction time once the ball is hit. I suggest you find some physicists that learn more then a math equation because they are showing why math is not a science..