THE MAY RATINGS SWEEPS : . . . And the Winner’s NBC--By a Nose

Top-ranked NBC scored the narrowest of victories over underdog CBS in the May ratings sweeps, winning on the final night of the Nielsen competition with a surge powered by “Unsolved Mysteries” and a special episode of “Cheers.”

NBC took the sweeps with a national rating of 11.9, with CBS a nose behind at 11.8 and ABC registering an 11.4.

Going into the Wednesday sweeps finale, NBC, which had admitted it was “vulnerable” after a “disappointing” season, was in a dead heat with CBS, the last-place network for three years. CBS had pulled into a tie earlier this week, helped by strong showings by the last episode of “Newhart” and the TV movie “Killing in a Small Town.”

But weak CBS performances Wednesday by the Joan Rivers TV film, “How to Murder a Millionaire,” as well as the shows “Comedy Bloopers” and “Sydney,” ended the network’s bid.

CBS, however, while losing the night’s battle, had clearly won the month’s war--coming out of nowhere to prove that NBC’s era of invincibility may well be coming to an end unless its new, comedy-heavy lineup takes off in the fall season.

NBC escaped total embarrassment when “Unsolved Mysteries” delivered 28% of the audience and “Cheers” 25% to wrap up Wednesday’s victory--and the sweeps--in the first 90 minutes of competition.

In the overall picture, however, the most significant statistics of the May sweeps showed that NBC had fallen off sharply in its control of the key, younger demographic audiences coveted by sponsors. In the past, demographic competition has often been a harbinger of how networks do in total TV households within several years. ABC and NBC, for instance, became ratings leaders after scoring first with young urban audiences.

NBC research vice president Bob Niles reported Thursday that his network’s ratings had dropped 18% in May compared to the same period a year ago.

CBS research vice president David Poltrack contended that, even more importantly, NBC’s audience of women and men between 18 and 49 years old had fallen off about 27% in the May-to-May comparison. In fact, he said, NBC finished third among the networks in that period with women 18 to 49.

While all three networks continue to lose viewers to new TV alternatives, the battle to control the shrinking audience of the Big Three remains fierce. Said Niles of NBC’s sweeps performance: “A win is a win. We may have won ugly, but it’s a win.”

Added Niles: “The real question is whether this sweeps is an indicator of next fall. No way. We saw these problems developing throughout the year, and Brandon (Tartikoff, NBC Entertainment president) took steps in the development of programs to renovate NBC.”

Poltrack saw things differently, saying that it wasn’t simply CBS’ cleverly programmed specials and movies during May that made for the surprisingly close competition.

“I don’t think it’s an aberration,” he said, adding that while CBS had held its audience from May, 1989 to May, 1990, NBC’s series were slipping. The only NBC shows that improved from last May, he said, were “Unsolved Mysteries,” by 5%, and “Cheers,” by 1%.