Not necessarily. For example, what if a teammate only "throws" a game when the game is already lost (but the game will likely last for another 10 minutes or so

Not necessarily. For example, what if a teammate only "throws" a game when the game is already lost (but the game will likely last for another 10 minutes or so) That wouldn't effect win rate very much, but it is still a bad player experience to be with a teammate who is intentionally trying to be bad.