Advantage consists of sub advantages, which are: spatial control, positioning, health, uber and death match
For now we'll assume that death match is the same for both teams, because when it is not, and for example your team has much better DM, then many of the other advantages don't need to come into play, if you just walk at them and kill them then you win. The problem arises once you meet people who have better DM then you, then you need to be able to fall back on your game sense and intuition about advantage.
Health advantage is a major one, if the entire enenmy team is weak, then if you walk at them with more damage you'll beat them even with the same death match simply because they will die to less damage