Since the distribution of good hands being dealt to you is a predicatable 15-20% you're still only playing the good hands. If you're not getting dealt ANY good hands, it'll be lower. And if you're getting dealt ONLY good hands, it will be high. However, both cases are rare oddities. So 15-20% is a good general indicator of what hands you are playing. (You don't have to force yourself to play within this range, but if you are naturally too loose, the number will be high and if you are too tight it will be lower.)

-'rilla