Sprint has plenty of capacity. Fact is, Sprint has three towers servicing KOSH year round with the nearest being close to the old cemetary adjacent to the field. Last year (Check the forums to take others' words), Sprint did really well comparative to others. To enhance coverage even further this year, Sprint has rolled two COW's and increased T1 capacity to the towers. Sprint's investment this year and last is well into the six figures.
I am from Sprint. I participated in the wireless carrier Round-table at the EAA HQ in January this year. Mr. Carrier, as he had shared in another thread, is doing his best to get the carriers to upgrade capacity and speeds and is fighting the fight. We (wireless carriers) are responding, yet there are ROI's to consider for the remaining 51 weeks of the year. COW's, COLT's, etc are designed to augment networks when placed appropriately, not replace networks.
I'm sorry if you are a Sprint customer and have a dropped call, or, a slower than normal throughput during a peak period of the event. No carrier for the matter wants customers to have bad experiences. Yet to date, no one carrier has unlimited capacity with gigabit speeds for all simultaneous users particularly in a highly concentrated event.