I noticed today that the links in the top Answerers and Askers page for a tag don't use the new is:Question
and is:Answer
search criteria, so they return both questions and answers.
In addition, the Last 30 Days links in the first column does not use any kind of date filter on the search results that would only return results from the last 30 days.
For example, click on any link in the columns indicated below from any topusers-for-tag page, and you'll see the results are not filtered, and the # of results returned does not match the number displayed
https://stackoverflow.com/tags/wpf/topusers
is:question
andis:answer
commands aren't "new" (they existed with the previous search), so I'm assuming they just never thought about those things when building these lists. I don't believe there is any sort of date filter option, you'd just have to sort by newest.