I think they cut it down to 86,000 so that they can charge more money. Plus the Maracana has not been fulling up as it use too 20 to 30 yrs ago. A lot of games, even the Rio derby(Fla/Flu), has been played in front of less enthusiastic crowds. Also it easier to control 86,000. They had already cut down seating to 130,000. because the Maracana had become decrepit and dangerous.