Balancer - data locality drops 30-40% across all nodes after every cluster-wide rolling restart, not migrating regions back to original RegionServers?

After doing rolling restarts of my HBase cluster the data locality drops by 30-40% every time which implies the stochastic balancer is not optimizing for data locality enough, at least not under the circumstance of rolling restarts, and that it must not be balancing the regions back to their original RegionServers.

The stochastic balancer is supposed to take data locality in to account but if this is the case, surely it should move regions back to their original RegionServers and data locality should return back to around where it was, not drop by 30-40% percent every time I need to do some tuning and a rolling restart.