Usually in these games, the term skill is used to describe an ingame ability. Press a key and you use the skill.But putting that asside, there are two forms of gaming skills, Physical and Mental.
Physical skill refers mainly to your reflex abilities. In an RPG, there is rarely much room for this, because everything is automated and controlled through hotkeys. While there is some room for physical skill of micromanagement (an RTS term), it is generally negligable and in many cases a macro or hardware device can surpass it. It's games like FPS is where physical skills shine, the ability to aim and dodge all require either talent or practice to be good at.
Mental skill refers mainly to strategy and intelligence. In an FPS, mental skills apply to adapting to your opponents play styles, discovering his weaknesses, memorizing and utilizing the terrain, knowing what weapons and options to use in a given situation, etc. There is alot of room in RPG's for mental skill as it incorporates all forms of tactics. Doesnt matter if how automated the combat system is, you are still required to decide on what to attack and what to avoid and to run or kite or whatever else may be involved. PvP wise, knowing when to fight and when to run is the difference between living and dying, but it's the large scale pvp when things take on a whole new perspective.
When doing, lets say, Guild vs Guild style PvP, think of every single player is as a unit. There are lots of points where skill mental skill applies from the tactics you decide to employ in the fight, to the way you form the groups, to the way you position your troops. Leadership is one of the most critical points, having an intelligent and strategic leader(s) capable of delivering orders and adapting to the situation is critical to the entire picture. Communication actually falls into the physical skill category, being able to type fast or being able to talk clearly is vital to giving out orders. The actual choice of choosing the medium, IE using TS is a strategic action that falls into the mental category though. Things like zerg tactics are also another form of mental skill application, it just utilizes a simpler tactic of overwhelming by numbers. Someone has to make that choice and while less leadership is needed to perform, alot more management is required to keep more people satisfied and under your command. I see people ***** about "zerg tactics" alot a bit too blindly, more like an excuse to give up, than a motivator to overcome, so I thought I'd mention it.
There is also what I call diplomacy. The ability to communicate and get along with other players is a diplomatic importance that also falls into mental skills (IE People Skills). Some game mechanims require working together with additional guilds to accomplish a common goal not possible on their own. Sure one can attempt a zerg tactic in this scenerio, but then you have the management problem. It's easier to command a guild of 100 and communicate to the leaders of a two others with 100 more under their command, than it is commanding 300 yourself. Keeping 300 happy, and even ensuring they meet your guild's quality standards becomes that much more challenging that may easily result in a lower overall quality of 300 people vs the other 300 from 3 guilds. Again, this is just one example of many I could come up with. Being able to decide when you need to work together and form things like truces and alliances is often vital, and an example of the use of diplomacy to tip the odds in your favor.
In Lineage 2 when I formed Inner Circle, I recognized that my guild alone cannot take a castle so we worked out an alliance with 3 other guilds bent on taking all 4 castles together and sharing. The game doesnt just end there, please take a look at Playing to Win's 4 page article at
Sirlin.net — Your source of shocking insights on game design » Blog Archive » Playing to Win, Part 0: Why Bother?. Just as predicted, other competative guilds were forced to employ deplomacy of their own and organize against us. And then we were forced to go the next step and things kept rising to a new level nobody was expecting the game to evolve into, and trying to manage everything among such global chaos is not easy. All of this falls right into the mental skill category, it's all based around strategy and the intelligence to form and reform them.
Hopefully that helped answer your question, I tend to ramble and I dont really organize my thoughts (I'm not writing a book you know), so this is for whatever it's worth. I guess the underlying point is that while there is physical and mental skill sets in gaming, mmorpg's are mostly mentally involved. You see people claim it takes no skill to play these games, I disagree with them. But you have to either be intelligent enough to see it, or be smart enough to work with others who are (afterall, dont most people join guilds with the intention of either getting loot, surviving pvp, or getting access to content they wouldnt see otherwise?).