Of course, it is very useful to know and to take into consideration all these stat indicators but that cannot replace the personal observations of your opponents. Never forget the human factor. That would be a huge mistake. First, you should notice what hands are played by your opponents, the way they play different hands etc. Second, you should know that the style of playing can always be changed. Never forget that a player who changes his playing style and uses some new moves will not match the previous stat indicators. In this case you need to calculate other ones. That is why you need to follow the style of playing of your opponents at the moment and adapt your game accordingly i.e. you should never rely only on your previous calculations.

Besides, you cannot rely on statistics only when there are not enough hands played by your opponent. On the other hand, there is no need to become a stat maniac. When you get some experience, you will know exactly what indicators you need during a certain game.