I heard the 'pro' stiffener view from a FIRST board member who was on the game design committee. I heard the 'con' version from a FIRST regional co-ordinator. The reason I want to know is the stationary goals as built are pretty floppy and it is possible to throw small balls through them, accidently knock small balls out, jam the big ball so far down the goal that it can be a problem resetting the field. Also I am afraid that it will be pretty easy to shatter the unreinforced PVC unintentially during vigorous game play. I think it is a reasonable question.