There is no way that the hillsides ever hold that many people. It is way way to unorganized, kind of like an unorganized parking lot on grass or gravel. You can get more cars in an area when there are stripes then letting people self park, the same goes for the grass area but it is even less efficient.
I have done some head counting of various full games for the hillsides and there are at best 600-700 on each or 2400-2800 total. That number is probably tickets alloted with people moving around or kids throwing the football.