Heads Up-Hands to Call With in Big Blind in Texas Hold'em

Hold'em for Advanced Poker by Sklansky & Malmuth has on page 187 a list of recommended hands to play in a heads-up match when you are in the big blind versus an agressive player. Specifically they recommend playing 40% of all your hands...and they list out the hands should comprise that 40%...

here is the question...some of the hands they recommend to play will be beaten more than they win in a two handed game as per work Michael Shakleford, aka "the Wizard of Odds"...hands like 7/8 suited or 3/5 suited... anyone know of any post or archive material where Sklansky & Malmuth may have answered this question already?

I suspect they someone has already raised this point to them and they have answered...but i can not find it by using the search tools...

thanks in advance