LoL. You are partially right. Teamwork is a hugely important determining factor in success. But you are understanding the importance of a balanced build to suit your play style in such a way that best compliments the team. Suppose the rest of your team followed the philosophy that they should do what they want and count on teamwork. PuG experience demonstrates that the end result is a bunch of cruisers loading up on the usual self loving abilities tickilng each other to death by boredom with a rainbow of energy weapons and transphasic cluster crap.
What skills you bring and how you invest your skill points is actually quite important if you want to be a contributing member of any team.
To the OP if you have only a MKI shield do not PvP until you have at least MK X....just kidding really. Just post your build and skill point allocation anyone one of us for the most part will help. Some of us will be more helpful then others due to experience.