You're overstating the case. McCain's 2002 score - 78, his 2003 score - 75, his 2004 score - 72. His lifetime ACU score was from being right back in the 80s and early 90s before he became the media's darling "maverick". Each year, his ACU score sinks lower and lower.
You're overstating the case. McCain's 2002 score
That may be true. However, the criteria is so narrow with under ten votes used in each year that a trend might not be gleened from a couple of years.