 If the batter hits it over the boundary on the fly, it's worth six runs automatically. But the fielder catches it, throws it back into play, and throws it on the field. He saved five runs. Now, why didn't he just catch it and fall? Well, you can't touch the ball and touch the other side of the boundary at the same time. So you've got to grab it, get rid of it. Before your feet touch the ground, the ball can't touch the boundary. You can't touch the ball while you're touching the boundary. So you've got to jump up, grab it, throw it over. Re-establish yourself in bounds and then throw it in.