As Miller tells it, he started to drift away from and reexamine the liberal mindset when they all rallied around Clinton in '98-99. Dennis Miller rightfully thought Clinton should have resigned or been removed from office and here were his friends defending the guy to the bitter end, and beyond. He questioned his political values at that point and found some of them lacking.
Unlike Crimmins, Miller is able to actually examine his political beliefs and admit the flaws. That Dennis Miller has moved to the right politically is great and as has been mentioned, must be a bit scary for the liberals who see their whole political structure slowly rotting from within and being abandoned by the people they thought they had locked in for life, like Dennis Miller. Ad hominum attacks are about all they have left now which will only alienate decent Americans even more. It's interesting to watch, even if it does get nasty at times but Dennis Miller can take care of himself and easily fend off the attacks of a Crimmins who is just a no-name Hollywood hack parroting the liberal line like a good boy, hoping for peer approval and maybe, another job.
The best thing that could ever happen to Crimmins would be for Miller to acknowlege this article and make a one sentence response the next time he is on TV. But, since Miller has had tons of writers over the years, if you informed him that Barry Crimmins attacked him in the Boston Phoenix, Miller's response would be "Who the heck is Barry Crimmins?"