Have to admit that I don't really understand your question.
I doubt that underwriters short the offering, either before or after the offering. They make their money on the ~3% commission on the sale, not trading around the offering itself. The "shoe" usually is sold on the initial offering date, especially for over-subscribed deals like FGEN.
Maybe some of the smaller houses try to game the process, but the big-boys are pretty clean, or they won't get future business. Do they try to get clients to buy some (or more) if the price goes lower? Sure, but they aren't going to risk any of their own capital if it really goes down. At least that is my understanding. Others who have been in the business (Robo?) may have a better description.
