Our hand of rag shammy does respectable numbers, I'm Ele and I actually perform better than I thought. I thought I'd be very bottom every single situation, but I can actually hang with the other DPS.
Any fight where I have to manage positioning and totems as Ele tanks my dps though. It makes sense that I do lower dps, it would be lower anyway because of totem management.
Shamans are a balancing tight rope because if you make them do too much damage, then there's no point bringing other classes. You could just have an entire raid of shamans all buffing each other.