When I am playing I don't notice what people say to me, and I dont' notice what I say to them. I listen to what the balls say. My focus is the table, and the table is my focus. Distractions are opportunities for you to improve your focus. If a little friendly banter sets you off, then you may be a little uptight. I don't know how leagues work, but if you ask for a rule about people talking to you I would think more people will talk to you to get you off your game. If I was gambling with some one, and they were a little tight, and asked me not to talk to them, I know what I would do, and it wouldn't be shutting up. Hell, a lot of the people I know will tell you nice shot when you hit it wrong.
