It seems
EA may have seriously messed up a MUT set which was supposed to allow you to trade in five elites at 85-86 for an 87 elite.
Instead, it turns out EA made a programming error which allowed users to enter any five players into the set which allowed players to trade in players for 87 elites for super cheap prices -- which ended up crashing their value this evening.
The auction house has been down all evening now with no communication from EA on what is going on.
Some players are reporting that they received bans for using the set improperly but there's no word on if those were just temporary bans or not.
Currently there is no timeline on when the auction house will be put back up, what will happen to the cards players obtained, and what will be done about the bans some were reporting having received.
We'll be updating this piece as new info emerges.
EA Posted an update: