I hate to say this but just because someone has been playing for a long time does not mean they will be as good as other players. If a player is not doing well that does not mean they are not trying to win, they just cannot beat their current opponents. Yes you get the occasional player that just betrays teammates or sits on a power weapon spawn but I personally do not see that often. Another issue is the fact that not everyone has headsets. You can't really formulate strategies with people who can not speak to you. You can only do what you can and hope for the best.
We are all hear to have fun. Just stick to that and I doubt you will care much for how your teammates play the game