The chart is based on a set of 5 cards. [5,6,8,9,T]
So playing basic strategy with the hands and dealer upcard given, just exhaust all the hits/stands possible with the remaining 2 cards. Add up all the wins/losses, divide by the number of hands played, and you get the expectation.
About the only thing made up in "Theory of Blackjack" is Griffin teaching the elephant the correct way to play a blackjack (Sue, the elephant in question, already knew how).
