They most definitely are not at 100%. There are days where the park seems normal and other days where you look around and wonder where everyone is.
That said, it doesn't have to be at 100% to have the same effect. If it now costs me $1399 for the incredi-pass to get Christmas week, a week I go because I have a guaranteed week. They are in effect limiting my decisions. Sure, I could give up the premium I paid fo the week and use it another. But the reality is now I'm bumped up to the incredi-pass or forced to buy at the higher price point. So while not at 100%, they'll be able to convert me to a higher revenue customer.