XF 1.5 After Import, User Post Count is strange

I was wondering the explanation behind this. We did an import and while the overall site post count is perfectly fine, member post counts however are weird.

For example, one of our admins who was already the highest poster somehow got a 20,000 posts boost.

Most members seem to have gotten boosted 5,000 or so higher. In the case of one our members, her post count seem to decrease from nearly 3000 to only barely over 800.

We did a conversion from mybb and IPB into Xenforo. Granted, we can just edit the user post count but I am wondering what exactly has caused this...glitch?