Idealy you are correct. But in this senate, balance probably does matter. For example, there is no way that this de facto democratically controlled senate would allow Ginsburg to be replaced by someone like Alito.
My point is that the replacements for Rhenquist and O'Conner probably shifted the court just a little to the right, but the way that we structured the deal, it makes it look like we're shifting it a huge amount to the right.
I don't care anything about balance, but I'm not the one with a confirmation vote either. We have to remember that democrats have two sets of rules, one for them and one for us. To them, the Ginsburg confirmation is ancient history.