Wrong, wrong and wrong!
The buff does not affect critical rating stat in any way. It adds +5% to critical chance. READ THE TOOLTIP!!!
As in, if you have 20% crit chance unbuffed, you'd have 25% buffed.
It does not require you to even have any critical rating stat on your gear.
And furthermore your whole comment is self-contradictory. It would be completely impossible to increase critical rating without changing critical chance, as critical rating adds to your critical chance.
If you don't know the answer then don't answer. Don't just make stuff up that has no basis in reality.