The post counts are supposed to increase over time for users. That's their "history" and stature.
The only thing that would work is an additional field in the database that also tracks post counts for users but would be resetable by the admins and would also decrease with post deletions and expirations.
I think the majority of users expect their post count to always increase over time so changing the main post count to very wouldn't be what most expect to happen.
