The "corporate ticket theory" does NOT explain the empty seats in the upper bowl. Scanning the arena while I was at the Texas game, it looked like those 4,000-plus empty seats were scattered equally throughout the upper and lower seating areas; midcourt and end-zone. There were empty seats everywhere, and this was the TEXAS GAME.
Besides, how many "corporate seats" are there. I sit 4 rows up from the court, just behind the scorers table at mid-court. I am NOT a corporate ticket buyer, nor are the folks that sit to my left or right, or below or above me. We are just OU fans that love OU basketball, and we donate the amount to get these seats.
My main point is that there are empty seats everywhere ... lower bowl, upper bowl, donor section, student section, ... everywhere. There are No-Shows, everywhere.
As others have pointed out, anyone can "come on down" to the lower bowl after the first media timeout. I wish more people would do so.