Note that overrides behave quite differently than pre or post. The highest priority override wins and it throws away any previous pre or post hooks. I submitted this as a bug through helpdesk about a year ago but was told it would break too many things to be done correctly (and semantically the same as pre/post). I suggested that an override simply override the original content and if there were multiples that they be concatenated together in their priority order. Other pre/post hooks would remain… Just two cents.
Note that since statistics just does ajax requests there is no reason for it to override anything. My guess is that is the defect they plan to correct. I would rename their top.override.tpl as top.pre.tpl.