The Importance of Entropy Regularization in Poker

In poker, the state has to be all the information that you need to make a good choice. In AlphaGo and in Deep Blue, it's a neural network where you plug in the board position,. But in Poker, what does it mean? What do you actually care about? Like, if I have a really bad hand, but my opponent thinks they're busted then this is not quite right. And those errors really do matter.