Ugh. I didn't want to do this.
First of all, let me say this: I know resto shaman are critically underpowered, especially in 10N which is what we're running. I know that some fights, such as Garalon, where everyone is spread out, are not good for resto shaman. And I am aware that just because someone is lowest on the healing meters doesn't make them bad -- someone has to be last. I get that.
I've been running with this guy for a while, and he's routinely our lowest healer by a substantial margin. My raid group is basically stuck with him for guild political reasons, so the only realistic solution is to find the problem and fix it. My only shaman is a level 3 bank alt and I can't really tell specifically what he needs to be doing, only that I suspect he could be doing much better.
I won't ask you to look at his gear because that's a whole different nightmare I don't want to inflict on anyone else. I am asking, specifically, for general resto shaman advice. So a shout-out for help for all you successful healers out there, take a look at what he's doing, and give clear, precise instructions as to what he needs to start doing/stop doing/replace doing. Because I really suspect that he needs help.
Huge thanks in advance for whatever help you can provide for his rotation/priority list.