Proposition is not arguing for all calls to be made via instant replay. Balls and strikes, for example, are best left to umpires because they are regarded as more subjective, and because there is no video equipment that consistently renders results that are widely viewed as accurate.  Besides, the human element that really matters is that of the players. The umpires’ human element might be substituted for making sure that the players’ human element is what decides the game. The point of the baseball game is for players to win or lose the game, not for umpires to win or lose the game. A baseball game played by robots but umpired by people would have lost its “human element,” but the same certainly would not be said about a baseball game played by humans and officiated by robots (or even just human beings who occasionally consult video footage and interpret it in their human minds).