gbaji wrote:
Yeah. While it's not like I've read the whole MLB rulebook or anything, my understanding is that if the batter leaves the batter's box before the pitcher begins his throw (perhaps even steps on the plate), the pitcher isn't allowed to pitch (ie: you can step back, stretch, grab your crotch, spit, etc, and the pitcher can't toss one in while you're doing it). Once the batter is "set", the pitcher may pitch, at which point the batter can't leave the box. Not sure what the penalty is if he does, but it's a violation of the rules.
The batter can leave the box at any point if they desire so. However, if they've "set", then leaving the box without getting a timeout from the umpire means any pitch still counts. Even the wildest of pitchers will throw down the middle if the batter's not standing in the batter's box.