The bunching is because of the zipper and not the jersey. Since the teeth are plastic and not fabric they will not fold. If the jersey is to big you should get it altered at a tailor shop. I'm a tailor and although I have never had to fix one of my own, it is a rather simple procedure. You could pay anywhere from $10 to $18 depending on where you go. I have done it before for customers and and they have all been happy with the results.