Do you play better when you are part of a team? I'm not certain about myself, but I know that joining a team has usually raised my rating. It happened at one of those other sites that served as a prototype for Chess.com, and joining Chess Association (now closing in on 1000 members) boosted my rating here.

It definitely do.  I tend to get bored with turn based and make silly mistakes in the end game or once I'm up a peice or two, but when it's a team match I stay focused (usually). 

I think the team concept is the best feature here.

I think I have improved by being in my group KCM due to experts in my team. They tutor me and I also learn from them through vote chess.

Chess Association is closing in on 1000 members. Who will be the 1000th?