They released it in the wrong time of the year. This shouldn't be a summer film. If they had released it in the spring or the fall, they'd probably do pretty okay, but it's going to get destroyed by everything else out there.
A 60% dropoff is never good but I think this one will do better than the other Hulk film because this one will probably have more longevity. Unlike the earlier Hulk movie this one is more of a popcorn action flick so it'll probably still make a good amount of money for the next few weeks due to repeat viewings by comic nerds and people looking for a fun action movie.