I love the attention to detail in this manga. The characters can tell the timing of the first pitch was dead on because the ball was a foul tip straight behind the batter. If he was late or early it would jump in a different direction. He was late on the second pitch so the foul ball would go to his "push" side, as Karasawa is a left handed hitter the ball ends up in the Seishu dugout down the third base line.