How to move a resource to a new resource pool and still maintain historical data associated with the previous resource pool?

We have been using resource pools in reporting when analyzing time tracking data.  It allows us to show how different teams within our IT department spend their time.  For example, we can show that the Tech Desk team spends the majority of their time on incident requests and operational tasks while the Application Development team spends more time on project and enhancement work. We have a resource who is moving into a new role on our Operational Support team from our Application Development team.  Once I switch this user over to the Operational Support resource pool, my understanding is that any of his historical time tracking data will now also be associated with that pool vs the Application Development pool.  Is there anyway to retain that from point in time A to point in time B his hours should be associated with Application Development? 

Thank you for your help!
Katie