I love the ability under User watch statistics to "Filter by page category" or "Filter by user group", however a wiki can have a lot of categories relevant to a group/department and MediaWiki user groups might be too coarse. Having the ability to filter users by a specific category like "Department" would allow managers of that department to view how well their reports are engaged in watching the wiki. Having a departments score aggregated would be another plus.
Similar to #9 (Filter Special:WatchAnalytics pages based on user groups).