Here is what happened:
1) A lot of people (brokers) thought the lineup was weak and started shorting the event.
2) They got stuck in what's called a "short squeeze" where it basically has become a game of chicken between those with legit tickets and those who shorted at prices at which they can no longer make a profit.
3) Some of the less scrupulous shorters put up dozens of listings to make it appear as if there were 800+ passes available on Stubhub. Those fake listings amounted to about 600 tickets and were taken down not too long ago by SH who realized what they were.
4) The low completed sales prices are, in fact, shorters original prices. At this point SH is starting to cover their collective asses by filling orders that have not yet shipped. Final ship deadline is tomorrow at noon PST after which you'll probably see prices take off as SH starts to fill unshipped orders from whatever inventory they have in hand at last minute services and elsewhere. However this is going to substantially deplete any inventory on SH. It also, however, will likely be the only legit market for tickets at $1300+.
5) Prices will settle around $800 tomorrow night (IMO) depending on what is left after SH fills the shorts.