Communication
 Reaction time
 Knowledge of the game
 Cooldown/timer managing
 Strategy
 Mental Awarness/ability to plan ahead your opponent
 Dexterity
 RNG

 Lets compare it now to quake live (or any other quake):

 QL:

Communication: CTF/CA/TDM requires a lot of communication, like any other fps

Reaction time: Reaction time has no limit other than PING and human capacity

Knowledge of the game: You have to know every map (a lot), the location of every item, as well as the tricks.

Cooldown/timer managing: …  More