werk said:At the cost of a feat with an Int prereq.
You could interpret Combat Expertise as an active defense that hinders the opponent's ability to counter attack, thereby making it more effective than just "turtling" with Full Defense. Of course, that then implies that expertise would only apply to that one opponent, when it actually affects all opponents, even those making ranged attacks against you. I agree it's a little wonky, but no big deal IMO.