That is a great question. The only extra flights I have ever seen due to any sport was for the superbowl and not every year either, depended on where it was held. They certainly do lose a lot of revenue from not selling what they know will sell out and be able to sell the full Y and full F seats to boot. They certainly can plan for sport events as they are scheduled long in advance. Maintenance and all can be rescheduled to accomodate the extra flights. Alas, it is yet another example of U not doing the logical move or even the financial move! If that mentality has not changed, no codeshare, no bankruptcy, no new labor contracts, and no new financing will save this airline. Too bad.
Perhaps U will be reincarnated as a true discount carrier with all Airbus aircraft within the US, as one person with lots of cash really wants to do. It's no secret that the owner of Virgin Atlantic, Richard Branson, wants to create a new discount carrier within the United States. Perhaps when US fails to show enough profit after emerging from bankruptcy, he'll have his chance to come in and buy up the routes and airbus aircraft too. Maybe then, those 330's will be flying into Heathrow.