All games have a slump between new content (I've seen in it GW2, SWTOR, TSW personally). Unfortunately, it also doesn't help a lot of new/shiny games are releasing.

Unfortunately, a lot of these are kinda core issues with MMOs: the social element/what to do between those patches. We find a bubble, and stay there (aka farm X until your eyes bleed).

Plus, FC pride. No one wants to admit defeat (and I got stuck running a small SWTOR guild that started with 20 people down to 5 in 2 weeks), and usually it's hard to recover from that.

Most pops perk up with expansions of new content, but decline in between hile people either ragequit, quit for another game, unsub and wait, or just get bored and need a break. Either way, ya can't change people, and that's the bummer.