We've added a new stat to the Rock Band Dashboard Facebook App - Skill Level. Your skill level is a number up to 100 that indicates your overall Rock Band skill. It is based on the number of stars you get on songs, and how difficult the songs were.
In more detail - songs you play on higher difficulties and higher difficulty tiers get you a higher score. Your scores across all songs and instruments are averaged to come up with your overall Skill Level.
So a devil-tiered song you play on Expert gets you more points than a two-ball tier song on Expert. Songs played on lower difficulties (Easy, Medium, and Hard) will also get you fewer points. All of this is averaged out to give you your overall Skill Level for Rock Band 3, or for each instrument. You can also see your Skill Level for each instrument.
Go check out the app for more stats and to check out your skill levels. Let us know what you think about the update below!