The TV Season's Ups and the TV Season's Downs

THURSDAY
NBC's comedies, led by the indefatigable Cheers, still dominate the night, but not with the bulldozer force they once exerted. Fox's The Simpsons has raided Cosby's audience, and Grandmay be TV's most disliked series: Every week, 10 million viewers make a point of turning it off. NBC's slight erosion has helped CBS woo younger viewers. ''The Flash can bring us a completely new audience,'' entertainment chief Jeff Sagansky said earlier this season, ''if it works.'' It's working: CBS' superhero action drama is now a top 25 hit among young men.

FRIDAY
This season, ABC retooled Family Matters to focus on nerdy Steve Urkel and turned it into the hottest show in its lineup of kid-oriented comedies. NBC competed by moving three established shows — Quantum Leap, Night Court, and Midnight Caller — to Friday. The result: They're all hurting. ''These are quality shows, but the ratings haven't been acceptable,'' says NBC's Simon. CBS is also making changes: Over My Dead Body is out, and the network's rescheduling of Uncle Buck was a disaster. ''We had hoped Buck would have a strong kids' following,'' says CBS senior vice president Peter Tortorici. ''That didn't prove out too well.''

SATURDAY
With baby boomers watching cable, renting videos, or going out, network wisdom has consigned Saturday programming to viewers who are too young or too old to leave home. That's why NBC's senior-appeal comedies, The Golden Girls and Empty Nest, have been the night's only big hits for years; for other series, including Parenthood and Working It Out, Saturday has been a boneyard. This fall, ABC has tried to lure 18- to 49-year-olds and made what Iger calls ''very modest'' gains. ''Clearly, the success we've had demographically (with Twin Peaks) has resulted in a more positive economic climate for us. But our approach with China Beach was incorrect — it was too intense for Saturday night.'' CBS has had an even rougher time; its E.A.R.T.H. Force lasted two weeks, and Wiseguy and Broken Badges aren't doing much better. ''I don't think it's hopeless,'' says CBS' Tortorici. ''We just need to be more sensitive to what people are looking for.'' For now, the night is NBC's, and Simon says ''creative adjustments'' on The Fanelli Boys and American Dreamer will make the lineup even stronger.

SUNDAY
The night usually goes to CBS — in its 23rd season, 60 Minutes has become TV's No. 2 show, and Murder, She Wrote is still beloved by older viewers. ABC's America's Funniest... hour is a big draw, and Fox, almost a nonentity on other nights this season, can smile through its growing pains at the continued success of Married With Children and In Living Color and the growth of Get a Life. That leaves NBC with no pulse; this fall, Hull High and Lifestories didn't even cast a shadow. Next month, NBC will try news shows in the hope that Real Life with Jane Pauley can snap its losing streak.

Executives at the networks agree that one hit could make the difference between first and second place, so in early 1991, the networks will air 30 new series in search of bottled lightning, including CBS' Good Sports, a sitcom about broadcasters with Farrah Fawcett and Ryan O'Neal; NBC's vampire saga Dark Shadows; Fox's Married With Children spin-off Top of the Heap; and ABC's adaptations of the movies True Believer and (after much delay) Look Who's Talking.

''If we do our jobs right,'' says CBS' Tortorici, ''the ratings will reflect it. What can we do to give people more of a reason to watch us? We can put on better shows.''