I was wondering if I was the only one confused.
See above.
FR ranks in the 1800 range of most frequently visited sites. DU ranks far lower, sometimes down around the 45,000 rank, and never higher than 17,000 or so.
In all the sites Alexa polls, only Drudge (300 something), and one or two other sites that I can't recall at the moment, have a higher ranking among political sites than FR.