The most important player on a baseball team would have to be the pitcher. Most games center around the pitcher and how effectively they are able to throw a strike. If they are not able to throw a strike, they increase the chances of a batter hitting the ball out into the outfield and potentially scoring points. So if you don't have a pitcher that can effectively throw the ball in a manner that is able to help strike someone out, or make it to where it is easily managed, you will struggle in the game. You also, in order to even have someone who can bat and play the game in general, you have to have someone that is willing to throw the ball at the mound.