If the campaign manager is only looking at the number of posts a user has when they go to grade the campaign and subtracting it from the number they had the previous week, then that manager is severely screwing over campaign participants.
The moderators have been doing an excellent job lately and deleting or locking a bunch of the mega spam threads making users posts counts change drastically throughout each week. So the managers, if they're doing their jobs correctly, should be opening each and every users profile and getting the post counts correct for each week. This also will allow them to take a glance at what a user is or has been posting.