The best Damage Meter read out is the one called "Idle Time"
If anyone has an inordinate amount of idle time compared to the other raiders, and never said why (aka he was here the whole raid, he didn't go afk for a half-hour), it is because he wasn't healing, cleansing, dpsing, tanking, or buffing for most of the run.
The other meters? They're useful as long as they don't become an idol.