In T-Mar's example we are merely 5-handed and there is just 1 over-card...and we're not really sure how to proceed.
Correction, your not sure.
"There is no doubt in my mind that medium pairs play much better pre-flop than post-flop. Apart from the 1 in 8 where you actually flop a set you will be facing overcards in 7 out of 8 instances, making it almost impossible to know how to proceed."
Obviously it plays best pre but still plays good post.
I've not read the book but i am guessing he aint playing this shallow.