Imo, if there is any one person in a guild that should be able to switch between specs it is the GM. I'm a lock GM myself and loved Demo but now it's gutted and to benefit my group I went to Affliction and do pretty well. If I decided to stay Demo and was pulling way lower DPS or bottom DPS then I'm not doing my duty as a GM which should be helping a group clear content.
I'd personally leave it alone. I mean if you were going for world firsts I could see you being a little upset but, I am just assuming you aren't so as long as it's not holding progression back I'd leave it alone. No sense in pissing him off over it and possibly causing problems for yourself.
Ive used destruction on 2 of our 4 heroics and affliction on the other 2. The spec seems very viable and actually sims higher single target in BiS t16 (gap actually gets bigger in a sim the worse your gear). I am going to go out on a limb and say you don't have a spec issue as all 3 locks specs are relatively close and fight mechanics matter more than anything (note - sparkuggz played destruction on their siegecrafter kill). Your issue is probably just player skill because if he isn't calling stuff out, etc. I don't seen him changing specs as all of a sudden fixing the issue.
I would say the issue you are describing is a player not performing properly > some oen takign a spec that can't perform. As you can see in the log I posted destro can perform with more than enough dps needed but if you arent min maxing then no matter what spec you play you will be underperforming.
Think of it this way... if he puts that little effort into a spec he likes to the point he does not want to change for potentialy more dps ...how little effort will he put into a spec he doesnt like?
I'd simply suggest him to take a look at the stickies we have since it sounds like his gear is not the main problem but his play style and rotation is. Also, it has been said multiple times already, but unless you are going for world firsts, you shouldn't be forcing someone into a spec, although you probably wouldn't need help then.
Edit: The new simcraft seems to have destruction ahead of affliction with BiS, looks like he's right about affliction being worse, although he might have different results with his current gear.
Since many locks who have been playing for say...the last 2x expansions probably have more experience with demo than anything else followed by affliction. Aff was the T14 darling. Pretty hard to argue with demo in T15! In dragonsoul many locks sat for mage alts so the few of us who were left played demo buff bot to the mages/healers. Firelands was almost entirely demo w' MWC or GTFO. Destro was only ahead for the first few weeks of T11 until ISF left affliction and it kinda steamrolled destro.
Point being that in terms of playing the min/max cheese (or work) the mechanics/numbers game most locks are experienced in demo or aff...at least far moreso than destro. Thus a swap to destro is simpler to execute a basic rotation but it has quite a bit of finesse in terms of getting those shadowburns havoc'd or whatnot.
Then again I got so much grief for using destro over aff on h.spoils I swapped back. Then destro shows up on blood legion's kill video so those same people probably owe me an apology (I'm not holding my breath but it is a "see I was right"). This prejudice is from a top 20 US 25m guild so its not exactly the uninitiated...just people chiming in who don't keep up with lock changes.
I agree with Werst in that most veteran locks are demo/affli. In my own pool of friends, everyone that rolled a lock in MoP rolled destro because it was the easiest spec to play. Most of the time, they never bothered with affli or demo.
As far as your GM goes, people can only be helped if they want help. That said, offer to send them to these forums or where other class guides are, offer to send them to askmrrobot.com or to wowreforge.com, and offer to help. If they don't take it, then there isn't much you can do. If that causes you to be unhappy in your raid team or your guild, change it up. Maybe your guild has a 2nd team that you can switch to, or go look into a different guild.
Archimonde's Darkness is not about getting one more Dark Soul per fight, it's about being able to line it up with trinkets without wasting cooldown time.
Destruction is perfectly viable, the thing is; warlocks can perform almost any task (is there anything we can't do?) depending on their spec and how they choose to play it. Affliction can be used for cleaving down adds, but so can destruction. Destruction is extremely potent when bursting down important adds such as Corrupted Fragments on Sha of Pride heroic.
It really comes down to what your guild/raidgroup needs and who decides that better than your own GM?
You should get him to play destro better.
Destruction is highly viable on normal. It can do massive cleave if just do it right.
Tbh get him to focus on destro, because odds are that if he can't do destro right, he will NEVER be able to master affliction.
So, my gm currently is a warlock. He has been all expansion. The problem is, he seems to be of the sound mind that destro is the best spec and the affliction nerf made it worse then destro. I told him it changed literally nothing single target and that destro is still worse then affliction, but he doesn't seem to care. I even told him all the best warlocks and simers say affliction is top, but still nothing. To make matters worse, he is honestly going to try to go from the KJC talent to Archi (double darksoul) talent, as destro. I told him its a dps lose and he may gain only one extra use of dark soul but I can't seem to get through. Does anyone know how I can get him to listen?
OP, I'd say the problem seems to be your expectations. Perhaps you want to be more hardcore than your guild does, and it's time to find a guild that matches your preference.
EDIT: Also, you're just flat out wrong in several of your statements about Warlocks (AD not being good, Destro not being competitive, current sim results, etc).
If your GM thinks he is special because it says "Guild Master" instead of "Member" next to his name then he needs to learn that isn't the case. In terms of guild politics, procedure, things like that, sure. He's the top gun. In a raid, he's a raider. Period. It doesn't matter if you're the GM or a new recruit, DPS is DPS. If he isn't pulling his weight then that's a problem.
What you need to ask yourself (and him) is this; if he were a new recruit, what would happen? If he had joined the guild a week ago and it was the EXACT SAME situation, how would it be handled? Would somebody coach them? Would they be given an ultimatum, like"find out what's wrong and increase your DPS or you'll need to respec"? In most cases it's simple - if you don't do enough DPS to contribute to the raid, you don't raid. Period. His raid spot should be based on performance, not guild rank.
You know what the best solution is? Link him to this post. Let him see it's not just you. Your comments about his level 90 talent choices and other things seemed very uneducated and honestly I'd edit in a comment to the OP saying you realize you were mistaken about that so people new to this thread don't keep commenting on that, but aside from that you have a very legitimate point regarding his performance pretty much CONTRADICTING his guild rank. Show him the thread. Let him know you were genuinely asking for help and not trying to troll him. Let him see that other people would consider it a significant issue.
You either need to deal with it and realize you're going to have to do something you don't want to do that might put you in an awkward or uncomfortable situation, or get used to it. Or I guess gquit. Those are literally your only three options. Happy pickings!
Actually single target wise, destro is quite competitive with affliction right now, assuming chaos bolts are well timed. And AoE wise, its often better. So unless your GM sucks ass as a warlock overall, I would drop the topic.
Just let him play whatever spec he enjoys, they are very similar.
I always raid as Marksman on my hunter, although alt runs and at like 8/14 normal on him, it's fine. There's usually something other than DPS that is wiping a raid, in my experience.
Aslong as everyones having fun it's all good.
And the fact that he doesn't seem to listen to you might be because he's stubborn or just tired.