What are "Popular Apps" on the Mac App Store? The Mac App Store features "Popular Apps".

The list even comprises apps with a rating of 2 or less.. which seems weird.
'Better' apps are not listed.. do we have any clue how this list is compiled and what's a "popular app" in terms of the Mac App Store?
Whilst apps on the top charts list are selected algorithmically, all the apps on the featured tab are hand-picked. There's no algorithm that directly chooses apps to be shown on the featured tab.