Nothing is perfect. Therefore, it follows that any replay system will itself be imperfect and will introduce its own type of error into the game. What's worse from a perception standpoint: getting the call wrong on the field or having replay and getting the call wrong anyway? Sooner or later replay will overrule a decision that was made correctly on the field. The call will be made, the replay will be viewed and a new call will be made. Then, after the game, or even during it, a new piece of evidence will come to light demonstrating that the umpire was indeed correct. Even though it will be rare, it will happen and that fact needs to be considered.