Could be a couple of things:
1. Upping the post count for staff so they always show first.
2. A LOT of pruned topics.
3. Starting over with threads whereby ditching all old content.

Ah yes.

I always wonder about how you guys are such prolific posters...
I only have about a thousand posts on my own forum.

Yes it's pruned posts from when the forum moved servers and from UBB.classic to "another forum" and back to UBB.threads. No point in carrying dead weight and out dated posts from 1999.

You would have thought however that the post totals would have been recalculated.