ANALYSIS : Fall TV: good, bad and Leno : Several genuine hits have developed, but other new shows are already gone and NBC is tanking at 10.

TV ratings haven’t toppled over a cliff this season. That counts as something of a triumph for the networks, given that they spent much of the last few seasons seemingly balanced on the edge of oblivion.

A few new hits have emerged -- real hits, not just middling shows that PR people and overexcited fans wish were hits. This list includes ABC’s sitcom “Modern Family,” CBS’ crime drama “NCIS: Los Angeles” and Fox’s animated “The Cleveland Show,” a spinoff of “Family Guy.” The herds are finding other fresh favorites too, such as ABC’s sci-fi remake “V,” CBS’ court drama “The Good Wife,” Fox’s exuberantly goofy high-school musical “Glee” and CW’s zeitgeist-grabbing “Vampire Diaries.”

But a reality check is in order. For all the good feelings stoked by these early successes, three of the five broadcasters, according to data from the Nielsen Co., are still down compared with last season among young adults, the demographic that advertisers care about most. ABC, CBS and NBC have all slipped, with NBC off 10%, thanks in large part to declines stemming from “The Jay Leno Show” at 10 p.m. weeknights. Among the freshman series that have already tanked are ABC’s fantasy “Eastwick” and the sitcom “Hank,” as well as NBC’s medical drama “Trauma.” Last week, Fox yanked the second-season sci-fi series “Dollhouse.”

Here is a guide to some of the lessons learned as the still-shaky network TV business lurches toward midseason:

Scheduling still matters. It’s become fashionable among TV insiders to think that the dark art of scheduling series will decline as more viewers watch programming on a delayed timetable with their DVRs. But Fox’s experience this fall has demonstrated that the lineup still matters. Under the guidance of scheduling guru Preston Beckman and entertainment president Kevin Reilly, the network has transformed itself from a perennial autumn also-ran into the current No. 1 network among young adults. The network is up an astonishing 23% among adults ages 18-49. In total viewers, it’s averaging 10.1 million, second only to CBS (12.1 million). That puts Fox in an enviable position for when “American Idol” returns in January.

How did Fox do it? “Cleveland” and “Glee” certainly helped. But a bigger factor was the decision to move the medical smash “House” from Tuesday to Monday, where it’s faced little serious competition (sorry, “Heroes”) and lifted a night that last year was sunk in the mire of two long-struggling dramas, “Terminator: The Sarah Connor Chronicles” and “Prison Break.” Fox is up 89% in young adults on Mondays. That’s the kind of figure you normally just don’t see attached to the TV networks these days.

Comedy is back -- sort of. The season’s most-watched new comedy, with 10.6 million total viewers, “Modern Family” proves that people will still show up for sitcoms if they’re cleverly written and well cast. “Cleveland,” meanwhile, has been able to tap into “Family Guy’s” devoted and seemingly insatiable fan base.

But the networks are still looking for that elusive, era-defining blockbuster comedy a la “Seinfeld” or “Friends.” Despite so-so ratings, CBS ordered more episodes of Jenna Elfman’s “Accidentally on Purpose,” evidently on the theory that the show will improve. Fox has already zapped “Brothers.” NBC’s “Community,” with Chevy Chase, has found some partisans, if not many viewers.

ABC has tried to refashion Wednesday as a comedy night, with mixed results. “Hank,” with Kelsey Grammer as a downsized corporate titan, has already been pulled. But numbers for “The Middle,” with Patricia Heaton as a harried mom, haven’t been much better. “Cougar Town,” with Courteney Cox as a middle-aged woman on the make, seems to have benefited from the “Modern Family” lead-in. Overall, ABC is up just 4% in young adults on Wednesdays -- despite the fact that last year the night was groaning under terrible results for the since-canceled “Pushing Daisies.”

Viewers love them some crime procedurals. Go ahead, make fun of CBS as the Crime Broadcasting Service. But the most-watched network has the season’s No. 1 new show in “NCIS: Los Angeles,” which averages 17 million viewers. Cutting-edge it ain’t, but the network’s approach to procedurals works.

Leno in prime time was a bad idea. Sorry to be so blunt, but there you have it. “Jay Leno” was trashed by critics as being a virtual retread of the host’s “Tonight Show.”

NBC argues that it saved tens of millions of dollars by scheduling Leno’s talk show rather than a costly prime-time drama. But those savings have come at an awful price. NBC has dealt itself dramatically lower ratings in two key time slots, not just at 10 p.m. but also at 11:35 p.m., where Conan O’Brien has shed many of Leno’s older viewers on “Tonight” while not making the program any more popular among young people. No wonder NBC’s station affiliates, whose revenues depend on ratings from 11 p.m. newscasts, are on the verge of revolt. NBC executives, meanwhile, have been backpedaling to the Hollywood creative community, insisting that they are not abandoning investment in scripted dramas.

In fact, it’s fair to say that probably the only people who wouldn’t mind seeing NBC continue the Leno experiment are its competitors.

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scott.collins@latimes.com