The batter's box is not an automatic safe haven as the batter's initial position is the only "protected" location.
Definitely a judgement call:
Had this happen twice this spring season, same batter same game. Our batter's fault. We tell them to freeze in the box if we're stealing 3rd. She took a called ball, stepped both feet out of the batters and got nailed square right between the shoulder blades.
Next time up. Same thing but keeps one foot in the box and gets hit in the back again. Ump calls her safe cause of the one foot in the box.
I understand the both feet but the one foot in and one foot out had me baffled. I was just happy she wasn't called out. 12U TB team