I think you guys are making too much of this, i've been here for 2 years and more, and i've seen my fair share of dips in activity and quality. But they always rise, i'm sure any of the Admins, and some mods will as well, that its mainly because we have no cricket games so there isn't anything really to "dote on."
Regarding the quality of posts, i've noticed it, hell i've even been dragged into it slightly of late...and thats generally because of lack of members! Tom's point about the Asian members who come here purely for downloads is true, and i'm sure most have noticed it as thier grasp on the English language is poor. I mean, they can still come here, but put it this way, would you go to a Russian forum and try posting? No. I'll make myself clear and say im no racist, i hate them, but the thing is this problem origionates from that area and the "regulars," are starting to be brave and wander out of thier safe little downloads world.
But as i've said many a time, the forum will bounce straight back into quality, probably near the time of a new cricket game, but until then you have to ride it out. Ofcourse you see members come and go, thats why we're a community. A community wouldn't function if things didnt change. Hell, who knows how long i'll be around, i think i've had a fairly good shelf life