Simple stat percentage question

[Novarcaine]

Ok. so lets say I am at exactly 33.3% Crit which is where I want to be as frost mage. I add a tier 3 Masterful corruption. Havent I now thrown off my 34% crit?

If I was at 500 Crit. 200 Haste, 200 Vers, and 600 Mastery to start then I should now be at 672 Mastery. Which now makes Crit only 31.8%.

So anytime I add a stat corruption, i need to recalculate everything. Or, if the crit percentages were really important to me, I would need to get other stat corruptions, gems, gear, etc to rebalance the crit. Right?

[nickseng]

1. You don't need 33.34% crit as frost. It's a cap, but you don't actively go for it.
2. Simply adding Masterful will not reduce your crit. Stats don't work like that. It takes your rating, and coverts it to a percentage, and it won't change unless your rating changes(i,e by changing gear/gems/ etc). Simply adding a stat wont do it.