Preflop all-in (No limit Hold'em theory and practice)

[CesareBorgia]

I'm probably missing something very important here.

You are in a pre-flop situation in which your opponent is all-in. You figure the situation to be such that he has to have either a high pocket pair AA-JJ or any AK. You are the only person left in the pot other than the opponent who is all-in.

According to "No limit Hold'em theory and practice", page 208, table 1 and page 209, table 2, it is correct to call with a pocket pair AA-TT or with AK.

Now, what I do not understand is that it is correct to call with TT. TT has slightly less than 20% of winning against AA, KK, QQ or JJ and against AK it is a coin flip. However, these percentages are no different for any other pocket pair lower than TT. Pocket deuces also have slightly less than 20% chance of ending up on top against AA-JJ and against AK it is also a coin flip.

What am I missing here?