As Comedy Central's Stephen Colbert and MSNBC's Rachel Maddow have so brilliantly illustrated, Fox News hosts love to brag about how well they do in the ratings when faced with any criticism. It's their own spin on “I know you are but what I am.”

Which is why this report on FoxNews.com's comparatively low traffic from Media Week's Mike Shields was so interesting.

Shields writes (emphasis added):

In the cable TV news world, Fox News Channel is a force to be reckoned with. So why does the network continually get its digital clock cleaned—by CNN, of all rivals?

On the tube, Fox's ratings are so dominant that CNN is turning to prostitution-tarred former New York Governor Eliot Spitzer to revive its prime-time lineup. In fact, Fox host Bill O'Reilly recently suggested that rival news nets are all but irrelevant, saying, “If you want to know what's really happening in America, you have to come here.” But with millions of Americans turning to the Web for more of their news on a more frequent and immediate basis, can that assessment actually be true?

Foxnews.com averages around 12 million or 13 million monthly unique users, according to Nielsen Online, rarely approaching the 35 million to 40 million uniques that leaders Yahoo News, MSNBC and CNN regularly deliver in aggregate. Some of that disparity can be explained away, as both Yahoo and MSNBC draw heavy traffic from their portal counterparts, and CNN benefits from traffic driven by CNNMoney.com and Sports Illustrated's site.

But even on its own, CNN.com consistently beats Foxnews.com by 7 million or 8 million unique users. Per comScore, the gap is even larger: 43.4 million uniques for CNN.com in June vs. 11.4 million for Foxnews.com. Plus, CNN.com regularly bests Foxnews.com in measures like page views, time spent and video streams—and it has opened an early lead in mobile (14 million uniques vs. 9 million in May for Fox, per Nielsen).

Those numbers have led some to wonder whether Fox's lack of digital success could eventually undermine its influence in American news—particularly as a younger generation gravitates toward getting its headlines from iPhones and iPads rather than TV.