The baseball field has the right, the left and the center area defended by players dedicated to those areas. Depending on whose baseball field it is, the players might encounter a simple fence, a hedge, a short wall or a huge, towering wall while running back, attempting to catch a homerun ball. Nevertheless, the function of the structure is to separate the field from the fans, rather than to be a part of the field. Thas is why I would prefer to use the "plot/zeď/hrazení za středním polem" rather than "plot/zeď/hrazení středního/centrálního pole".