Sorry, but you are in fact very wrong. It's simple to do the math, but some people apparently have troubles with percentages.
If you do 1000 damage, then apply the 22% damage buff of expertise, then apply the 18% damage reduction of opponent's expertise, you do 1000 damage.
(1000)*(1.22)*(.82)=1000.4
Before, expertise reduction did more than the damage boost. It was not even. Now it is.