Yet it still hasn’t explained who’s unfollowing us.
TwitQuit gives you access to all that hidden information. Sync it with your Twitter account and you’ll receive statistics via daily or weekly email about every person who has followed or unfollowed you, when they did so, and a chart of the changes over time (very handy for businesses).
If you opt out of the email, there is an online version that shows the same information along with a list of people you follow who don’t follow you back and visa versa. You can even automate your account to auto-follow new fans or auto-unfollow departing ones.