In the big tournaments, everything you do while playing poker will be noticed and the players have the deep analysis about your character and behaving on table so yes it is very important to be unpredictable and never show any kind of emotions when you get good combination of cards or the worst one then only you can bluff with the bet amount.
Most of those gamblers around you are just simply trying to read you out.
Some might try to give you the win that you wanted as they are trying to assess your strategy, it's best to have a plain expressions and keep it that way, experienced gamblers most of the time take a little longer assessing you.
Winning with this people is like palying against yourself, as in any moment you'll be catch offguard and snatch the win from your hands.