I collected the charts for the top Facebook apps and posted them below – overall, there seems to be a general decline. Note that this may NOT be a bad thing – perhaps developers are getting incented to create deeper and richer apps – more details below.
Anyway, looking at these charts: Why is this happening?
A couple thoughts:
- More apps means more competition (even for the top apps), which creates fragmentation – it become harder to keep any good thing going
- Changes to the Facebook viral channels are continually driving down the response rates, incenting developers to create stickier apps that can retain more active users
- Continual use/abuse of the Facebook viral channels are making users cynical, driving down response rates
- The top apps have hit the "carrying capacity" of the Facebook userbase, and have saturated the entire network – thus, the only option is for the usage to decay over time, since more viral growth isn’t an option
There’s probably multiple explanations here – note that for some of this, Facebook may be "guiding" the developers to create more meaningful applications via this "active users" metric, so even if the top apps are losing users, that’s OK.