They are ranking the senators based on a grand total of 5 votes and penalizing every Democratic senator 10 points for unanimously agreeing not to filibuster Gonzales - essentially converting the Gonzales vote to be a -20 for all who voted to confirm and 0 for those who voted against him. (They only look at the Rice and chertoff, and Gonzales confirmation votes and the vote to certify the election and the class action law suit.)
Only 3 Senators are in positive territory, though some like Kennedy are at 0 - how do you take seriously a 0 rating for Kennedy?. The 3 that are positive are Boxer at 20, and Akaka and Kerry who are at 2.5. The latter 2 benefit from not being there to certify the vote. So they are penalized -7.5 for being "AWOL" - nice choice of words? Those who voted to certify the election were given -10.
So at the current time looking at the scores, only Boxer looks good. In fairness, it is February and any yearly score can not be looked at seriously - might be a good idea if they used a rolling 12 month score. At least at this point, the score card is being used only as a stick to hit the Senators with.
http://patrickhenrythinktank.org/sen-scores.html