just gives the percentage
of time a player wins the hand given that he saw the flop.
This number tends to be lower than most people expect.
Imagine, for instance, that about 70 percent of the time you
see the flop heads-up and the other 30 percent you see a
three-way flop. (These are reasonable numbers for a 6-max
game.) If you win half of your heads-up pots and a third of
your three-way pots, your W$WSF number will be about 45
percent.