Wow, this got reported by a lot of people. I'm going to reopen this to add my two cents.
In virtually any standard role in WoW 40-man raiding, very little skill is required from the individual player. The challenge is in the teamwork and execution of a larger strategy, and in some fights, in managing multiple "easy" tasks at once in the face of various distractions. Hitting PoH periodically is easy. Hitting PoH while dodging a Blizzard somewhat less so. Hitting PoH while dodging a Blizzard while keeping your group in range further so. Hitting PoH while dodging a Blizzard while keeping your group in range while staying spread out while remaining alert about nearby ice blocks so that Sapphiron's breath doesn't kill you? Still fairly straightforward, but that takes a bit of practice. When you just focus on damage, you're focusing on one small piece of the puzzle. And the fights you listed are all pretty straightforward in that regard. Except for running out on Anub and dodging RoF on Faerlina, which he's done on his normal character, it's really just a matter of standing there and stabbing things.
There are some exceptions to this rule, like frost nova'ing DKs on Gothik or kiting on Gluth, where you have very little margin for error and the learning curve is steeper, and raw skill becomes more apparent.
DPS is largely about paying attention. That's all. Your friend was focused because he didn't want to screw up, he wanted to see how well he could do, and maybe he wanted to prove something. Random Rogue X who's running the zone for the 20th time and has long since worn out the print on his backstab key may not be that involved or attentive on the 20th trash pull of the night, or even on many of the bosses. So much of "skill" in raiding is simply a matter of paying attention.
I would also propose that skill is more to do with the types of judgement calls, and the frequency thereof, you have to make on any given encounter.
Tanking a Garr is completely trivial vs. Tanking Nef without fearward, or Anub/Emps where you have to move your ass fast at the right time. Fluid positioning.
Nuking 1 raid boss as a caster is mainly mashing a limited set of buttons. Skill is much more evident when you have to be switching nuking multiple targets to stop the raid being overwhelmed, eg. Nef Phase 1, Noth. To a large degree thats why Razorgore was such a tough challenge when BWL came out, (excusing the lag/bugginess/tuning), its a different paradigm
Your basic heal rotation is just spamming, some Patchwerk strats are just chain casting one spell for 6 mins, anyone can do that, but on fights where you have to heal the tank, yourself, your group, and be efficient about mana, you are suddenly doing a lot more.
I know I could play a rogue on a stationery fight with a script like that and do well, the key is there weren't a lot of judgement calls for him to make, and on average DPS classes probably have to make fewer than healers. Could I perform on a fight like Gothik with those instructions? Definately not in the league of someone with months of experience, assuming they were any good to begin with.
I have to say I agree with most of what's presented here, the basic points of playing a Rogue; Building CP and Expending it is very simple, the maths was done a long time ago, and most people will do that same thing for the same result.
The more involved part comes from:
Gear selection - Not hard, but not everyone's willing to even take the time to download a spreadsheet and run through what their options look like.
Judgement Calls - The killer point, yes you 'may' be able to do decent DPS on a static fight like Patchwerk, but on a fight like Gothik do you understand where you're needed most, when to stun etc..
DPS is easily quantifiable, and it's easy to fall into the trap of judging a player based entirely on their performance, but when it comes down to one player having worse gear than another, this takes a lot of that analytical validity away.
I've played a healer in Raids, it's not all that hard, by Click casting I was able to heal BWL, top the meters and watch TV all at the same time. That's not to say that I don't apply attention as needed, but that every class can be broken down in similar fashion, we've had tanks set themselves to start attacking Garr then just afk since they'll have solid aggro by the time the raid gets there anyway. Each class has their simplistic aspects, it's the choices that you make in the new and hard encounters that matter as to whether you're a good player, not following a script for a static encounter where the only variable for a Rogue is where Patchwerk's back is facing.
one important factor I didn't see people mention here that comes up often between "good" and "bad" players is often just as simple as their connection and their hardware. Otherwise I definitely agree with most of what's been said here. This game is easy on the individual level, the challenge is in making it all come togather to beat a raid encounter.
A lot of skills across classes are transferrable. All classes will learn early on about optimal cooldown popping in a fight, whether it's with a ZHC or Adrenaline Rush. All classes learn to Heigan dance in the same way. All classes will have a basic idea of threat mechanics.
I've always felt that the first 10% of the effort you put in will net 95% of the DPS you'll ever do. The next 90% of effort is what gets that last 5%.
Easy game to learn, hard game to master? I have to agree that a good player will have good results no matter what class you put in front of him, but it takes a bit more to really master it (to get those last 5% as Maynard put it). Take the OP's friend, put him in a fight that requires more judgement than the basic algorithm of the class can offer (Gothik dead side for example), and I think there will be a clear distinction in performance between him and someone who main plays the class.
It's true that most raiding does not come down to individual skill, especially since it involved very few decision points, as some people have mentioned before. One of the more interesting parts is the Triage quest, for getting 225+ First aid skill. This requires you to make decisions, and accept losses. While I didn't take much note of it myself, my ex-gf spent 3 weeks before she managed to do it. While i think she is getting a hang of it now (after 2 years of playing), she wasn't an experienced gamer when she started WoW, and would often get herself killed on even simple fights.
A friend [...] having played a warlock in end game raiding
What over 2 years of playing WoW was going to be so learned, so practiced in your 5/5/3 or 5/5 rotation over a talented neophyte with the "script"? Squeezing out little notches here and there - little gimmicks for when you could optimize heartbeat ticks and so on before stepping out of AoEs and cleaves and such? They are, by definition, little notches. If he was skilled enough to be paying attention to more than just his own little microcosm (that is, he could raid brief someone not in his class "how the encounter goes"), then this is absolutely no surprise.
The major "skill" element of WoW is, in my mind, highlighted in bold. How fast do people learn and adapt? As a warlock, paying attention to the raid, he had already done all the learning, and as a rogue just needed some minor adaptations (as a handy example, I imagine ducking is vastly easier for locks then rogues for Chromaggus - but it's not exactly rocket science either way).
Edit: I believe the post above mine has an incredibly sharp observation, so I'd like to underline it. Well, bold it, anyway. I hate you underline!
Originally Posted by Grubsnik
One of the more interesting parts is the Triage quest, for getting 225+ First aid skill. This requires you to make decisions, and accept losses. While I didn't take much note of it myself, my ex-gf spent 3 weeks before she managed to do it.
Everybody is your brother until the rent comes due.
Bare in mind he's gone from DPS to DPS, so it's not a massive change, also bare in mind that half of the player 'skill' is employed before the fight, it's the micromanaging you've done in gear setup, enchants, talent build etc.
We had a similar situation not long ago, a lot of the guilds officer are RL friends so they sometimes switch characters. A resto shaman took on our best rogue for a night and you couldn't even tell it wasn't the rogue playing.
DPS is in general relatively easy, that's why it mystifies me when you see rogues in similar gear doing vastly different damage. The 'hardest' parts of DPS imo would be optimising threat management (horde only), and mana management in really long fights - neither of which rogues have to deal with (beyond pressing vanish at 70% :P)
The only really indepth side of DPS is energy/shot/cast cycles, and even then the WoW equivalent of a scriptkiddie can figure that out with a bit of homework. What catches my eye in terms of DPS is not the damage they do, but rather their movement and awareness of the surroundings. The first guy to the next add, the first to kidney shot, the last to pull aggro - those are the elements that reflect a modicum of skill and attentiveness to me, not their position on the meters.
Now healers, that can be a totally different story. I have enormous respect for the best healers I've played with, because when they're at the top of their game they deal with a helluva lot more than any DPS'er ever will. And on top of that, they get blamed for everything.