Infected often run circles around the player while slapping them, requiring you to back up and block to make the infected attack you as intended. They have a chance of running through the player and hitting you in the back. They can hit you from too far of a distance and they don't have to be facing the player to slap you. Once the infected get close to the player their behavior could change making them either slow down for stability or perhaps other methods. The infected worked better in older patches of the game back around the time sledge hammers were the meta as a reference of time. Maybe the devs could use the zombie runners from Dead Island as a basis, studying their game mechanics to refine or rework the infected.