I don't tend to write a lot of "hard" science fiction, but that's an apt descriptor for this story. Its basis is the very real biomechanical principles which state that pitchers are bumping right up against the limits of what the human arm can do in terms of speed on their pitches. While average speed has increased over time and there is some dispute about the reliability of various types of speed guns for measuring the speed of pitches, there has simply not been a dramatic increase in the top speed pitchers have reached in the past 50 years. (One list of "fastest pitches" is at this link.)
The reason that this record isn't constantly falling as other sports-related records (such as the sprint times in track and field, marathon times, swimming times, etc.) is because the human arm just can't throw a baseball any harder than it already is. As the article notes:
"Shoulder rotation in baseball pitching is the fastest motion of any joint in any athlete," Fleisig says; moving faster than hip joints in sprinters or shoulders in elite tennis players.My story starts from that science and wonders what would happen if something gave batters -- who are currently limited by their ability to process information about the incoming pitch and react to it -- an insurmountable edge against pitchers.
I hope you enjoy reading this story.