One Major League Baseball team has nine players on the field. Which one is the most important? Defend your decision. I think the most important player on a Major League Baseball field is going to be the pitcher. He controls the flow of the game. He controls the entire game. He can throw out on first, second, or third. He can substitute for first, second, or third if he has to. He can rush the base. The pitcher is, in my opinion, the most important player on the baseball field.