My favorite part of that article is the very fine chart above. It's meant to demonstrate how far NBC has fallen lately, but if you step back from the current media frenzy of "Woe is NBC", what the top chart says to me is "Woe is Broadcast Television". (I have my own similar chart that I do annually with a bit more detail, but nobody does business graphics that look better than the NY Times)
And while the bottom chart says "NBC has really slid in the last 8 years", it also shows that NBC's been in worse relative shape before (as have the other broadcasters) and recovered from it, so their relative position among broadcast networks is almost certainly temporary. (I have my own chart showing the cyclical nature of the business in the Eras of Network Television, and while it's not nearly as fine as what comes from the NY Times, it was put into a recent book on the media industry).
Note that the ratings in the two big charts above are household ratings, not adults 18-49 ratings that we and the rest of the industry typically cite. Most of the long term historical Nielsen ratings we have are household ratings, and perhaps the NY Times is in the same boat. And it seems to me the text above the chart is in error, implying that NBC hasn't been this far behind in 15 years, when the chart shows they were #1 in 2002. I'll have to look and see if I have the same series of data to verify.