Certainly Thursday’s results continued the scrambling for explanations of why most long-established shows have taken a nosedive, including such hits as “Grey’s Anatomy” on ABC, “The Office” on NBC, “The Big Bang Theory” on CBS and “American Idol” on Fox.

The ratings among 18- to 49-year-olds (the audience advertisers value) were truly eye-popping in some circumstances — and not in a good way. “Grey’s Anatomy” hit its lowest rating ever. So did “The Office.” And “Idol,” which had shown signs of stabilizing in its most recent editions, plunged again, down 14 percent from last week and an impressive 34 percent from the same night a year ago.

“Big Bang” which has been on a steady upswing, suddenly dropped 11 percent.

Ratings take a nosedive during sweeps month? OH GOD. We blame either Aereo or Oprah. (ht @AntDeRosa)