Football: A Naive Approximation to the Effect of Increasing Goal Size on   the Number of Goals
  The effect of increasing goal mouth size on the number of goals scored in a football match is discussed in a very preliminary and simple way, considering elastic collisions of the ball with the posts. The result is obtained on the basis of data taken from the Spanish Professional League, that show a high number of shots-to-post. Surprisingly, there is a direct correlation of the increase in goal mouth area with the increase of goals. 
J. Mira