it was "most files" before and now it's "most episodes". note the difference. if groups rel 5mio and 10 versions for the same darn episode the count of released files is obviously higher. people requested a "cleared" count hence episodes get counted now.
In this case, it's because for a long time, AHQ released subs in a separate file (before turning to ogm and then mkv). With sometimes even an additional .nfo file. Hence a high number of files for around half the number of actual episodes.
And a group (or maybe some) are hidden from those stats. Like RG that requested not to be shown. They were at the top at those times and they might still be.
They even wanted the removal of all their files, that was politely denied.