[gardarh]

The problem with the battery statistics is that even though an app that is causing battery drain it might not be registered with that app. Imagine an app that sends a 1kb probe message every 15 seconds in the background thus keeping the radio alive the entire time (i.e. never allowing it to idle). I believe that the battery drain caused by the radio usage would count towards "Android System" and not the app when in reality the app would be shortening your phone battery lifetime significantly.

Assigning battery usage to apps is a hard thing as there are so many grey areas. OTOH you will notice apps that are stuck in CPU expensive loops that will not terminate, however this is not that common in my experience.

The Android battery statistics are nice but they usually don't provide me with a useful answer to the question: Which app is really draining my battery.