There is a huge difference between fanboys predicting box office results, and people who predict for sport. Boxoffice.com forums, world of kj, filmgasm, mojo and a few other places are forums of people who only predict box office...for every single movie that comes out. They're pretty good.
The fact that Man Of Steels average predict. among more established predictors is in the 300m range speak, & it is a non sequel, for itself. W.B. have a big hit on their hands.
While nobody saw Avengers doing quite as well as it did, myself & a few others all thought Skyfall was going to do 300 millionish.
Anyone worth their salt should have known TASM wasn't going to touch the previous films. In fact, it's 260ish finish is a lot higher then most anticipated it would go. It also in the same mid 200s area Batman Begins & Superman Returns inflate to.
Though there are intelligent predictors at other sites, KJ has the best 6-7 predictors on the web. Comparing them to box office theory is like comparing professionals to amateurs. For both weekly analysis & long range predictions, they're the best. Anybody interested in box office should eye the posts by 'Dr. Lecter', 'Magnus', 'Xaiyun', 'Zingy', 'Madgez', and a few others. Most of them have decent real jobs involving statistical analysis & just do this for a hobby, and have for a while.
http://www.worldofkj.com/forum/viewtopic.php?f=12&t=67194
The general consensus for TASM was 125-140 for the 6 day, 250m ish total. Most of them saw Superman Returns flopping too, actually. General sentiment before tracking was released (which showed supes opening to 100+5 day) was 80/200ish. Right what it did.
I wasnt there for Batman Begins - but they all saw The Dark Knight and Avengers breaking out, though nobody thought they could go as high as they did. Most of them are feeling a similar break out vibe for MOS after the trailer.