In a Little League game I had today, the batter swung at a pitch, the ball hit him in his knuckles mid-swing, and the ball went about ten feet in front of home plate. The kid went down immediately, and I called a foul ball. The kid ended up being switched out from injury and a replacement was brought in to complete the AB. Regardless, should this be a foul ball for the ball going off the batter while in the box? Or should I have let the play go as a fair ball?