The flight of the Lamanites apparently led to confusion in the ranks. When the army was confused and in flight, they would be less able to effectively engage their enemy. Thus the pursuing army has all the advantage. It is not, therefore, overly surprising that there were no Nephite deaths, and the Nephite army would have the advantage of better organization and coordination in the attack. Even though there were no casualties, we should not suppose that there were no injuries.