His career WAR is low for a HoFer, but there are HoFers with less than him. He will get in for 2 main reasons...
His WAR is low due to a lack of longevity, and poor defensive and baserunning scores. Voters have a positive recollection of Vlad in both areas, despite a few dumb plays here and there I think he gets the benefit of the doubt based around the peak performance of his bat.
And second, and perhaps most important, he has the distinction of being a 'clean player' during the height of the steroids era.