Actually this feature exists but there a bug if you use the template tag {$this_period}.
For other users so they know whats up...
In admin settings under "Ranking Period" you have a option called "Overall".
This feature works as intended. But the template tag {$this_period} which display pv, in or out based on the method you select on the rankings page ( rank by hits in, out, pageviews ), will display always daily if you rank by overall
What does this tag do?
1) You rank by overall hits in
2) You use {$this_period} in the rankings files to display the hits in number
2.1) On rankings you click "Rank by Hits out" and the tag will display hits out numbers
2.2) You click "Rank by pageviews" and the tag will display the pageviews
So, it switches between the stats values based on what the visitor want the list to order by
Now the Bug is...
That tag will display stats from today, not overall. So instead of overall values you see daily hits in when a visitor clicks "Rank by hits in", and daily hits out when he clicks "Rank by hits out"
This need to be fixed