Any serious poker player knows that the best strategy for winning is to make your opponent make mistakes while minimizing your own. One of the primary tools for accomplishing this is the use of deception.
Once the game is reduced to calculating the odds at any given moment and betting when they're in your favor, even a simple machine should be able to beat a human as long as it makes reliable calculations.
It should really come as no surprise that a machine can beat a human at a task that machines are really good at.