Competent player > Incompetent player.
I've seen some stacked PUGs on my server, so it all depends on who's running with who and the level of communication. Hell, we'll run premades of 4 different guilds and it'll look like a pug, but we dominate..
Ugh, I thought we went over this. The people here aren't saying "Weak class, I can'ts killz nothin' so it's got to be the class!" Some of us here are top commando/merc players on our server, or atleast have decent track records. The reason we (and BW agreed) say commando needs some work, is because we also play other toons. Other toons, other specs, other roles, etc... Comparing between our toons, we've all found that on the dps Merc/Commando, we are always the least effective.
It's not "Can't kill that guy, must be my class." It's "Sure I can kill people/defend/assault/dance... but I can do it much better on any other toon/spec."
Mercs are support role class, people aren't playing them correctly. In good hands like yours, they can be absolutely devastating and Pyro Mercs are very viable. I have a guildie who runs it and he tops the DPS charts as well.
Arsenal has it's own issues, but I've seen Arsenal players do extremely well. The problem is that they think that they should act like a rotating turret. It needs to be a TM TM TM, move, railshot on the go, Proc'd Unload. The more mobile you can make yourself, the more effective you become. Hug corners. Little things like that.
Now, I'll ignore for the moment that you're a non-merc/commando telling players how to play their classes.
Dps Mercs are -not- a support role class. I mentioned this earlier when I explained support. Any dps can "support" another dps. Let one take point, the other follow, etc... But why have 1 strong dps and 1 weak one, when you could just have two strong dps? A maurader and a merc could team up (merc supporting the maurader), but the team would be better off with a maurader being "supported" by a sniper. The sniper will have better survivability, be harder to lock down, won't have to rely on "hugging corners" and even has a team defense buff.
A support class/role must be something that acts as a force multiplier for the team. If you look back through my posts you'll see I've explained this, but I'll recap.
A healer is a force multiplier. Alone, they're only really worth .75 of a unit, easy prey for a dps (our whole 1 unit). However, a healer adds .25 effectiveness to any unit around them. So in 2 vs 2, the healer is .75 effective while their companion is 1+.25 effective, or a solid 2 vs 2. In 3 vs 3, it's (.75+1.25+1.25) 3.25 vs. 3... etc...
A tank works much the same way, except I'd say they actually decrease the effectiveness of the enemy. Once again let's say a tank is .75 of a unit by itself. Has survivability, but little damage and it's support to a team is useless 1 vs 1. Throw them on a team though, and they start decreasing the enemies effectivenss by .25, 2 vs. 2 is (.75+1) 1.75 vs. 1.75 (1+1-.25). 3 is (.75+1+1) 2.75 vs. 2.5 (1+1+1-.5) and onward.
Now, a dps merc has no force multiplier. If they are left alone to dish out damage it is because of an idiot opposing team, not because the player or class has actually done anything. Dps Mercs are not designed to heal, buff, protect, or debuff. They are not designed to fill any sort of support ability. If they were, their off-heals would be better and less costly, or their heat signatures would provide +% damage to all damage on the target.
So... not trying to be rude (we've had differences before) but please explain how you figure a Merc/Commando is simply being played wrong, and their suppose to be "support" without any actual support abilities? Why take one as "support dps" when the role can be filled more effectively by a sniper?