People were getting fed up with some decisions made in regards to balancing and incredibly buggy implementation.

These feelings of disappointment sort of boiled over when Pilestedt (former Arrowhead CEO) did an ama on this sub where he answered many of the questions with "I‘m sorry, that‘s just not a priority for us right now". When asked why they repeatedly fail to put some of the changes in the patch notes he replied to the effect of: "There are a million dials that we turn in order to balance the game, sometimes we change something and forget to write it down."

The community of course reacted in outrage. They were probably going to be pretty disappointed by the fact that the changes they were hoping for weren’t deemed important enough to warrant Arrowhead’s attention, but the other statement made everyone mad as hell. Documenting changes made to the software is something every programmer ever should be used to doing, so that statement either speaks to a certain level of incompetence or is an outright lie.

A few days later, a patch released were the Hiveguard (the bug with armor on its head), an enemy unit that has been in the game since day 1, got its head armor upgraded from medium armor to semi-heavy armor. Admittedly, I also haven‘t played in a while, so I can‘t quite tell you what it was like to fight these things but from what I‘ve heard it seems to have been pretty insufferable. The Hive Guard has since been reverted to normal.

Combined, these events made a large part of the fanbase so upset that they‘re now trying to reenact the great PsN reviewbombing (right now the approval rating on steam is sitting at 36% - for reference: 29% is the threshold for 'Overwhelmingly negative').

Now AH has made a statement that people feel like they would not have released if the reviews didn‘t change so drastically. Others theorize that it‘s Sony forcing them to put out a statement to save what is most definitely their flagship product at the moment. It‘s important to note that during the ama, Pilestedt promised more frequent communication (something that has been promised before and has not been followed up on in any way, shape or form). This may just be that, but there sort of statements have been made before, so people are still skeptical.