Balanced Supreme Court?

I don't know that much about the Supreme Court. I listened to a book covering the important Supreme Court cases - which was interesting.

Anyway, I remember hearing talk of this article somewhere, so I dug it up. The main point that stuck with me was:

In 1980 Stevens often operated as the Court's median member; in many cases he (along with Powell) was the Justice Kennedy of that era. But Stevens is frequently described as the most liberal member of the current Court. If he qualifies for that position, it is not because of any significant change in his own approach, but because of a massive shift in the Court's center of gravity.

Kind of boggles the mind what we think of "liberal" now.