Effectively, this season of “American Idol,” the ninth, is the show’s last. Simon Cowell, its godfather figure, responsible for dashing the ambitions of untold singers and for being the most visible advocate for music criticism in this country, will leave after this year’s finale, in May, to prepare for the United States debut of his own singing competition, “The X Factor,” next year.
Even in retreat, though, he’s the show’s bread and butter, its most reliable source of wisdom and intrigue. Last week, in a conference call with members of the news media, he talked about what sort of winner he’s hoping for this year.

“You want somebody who represents what is going on at the moment,” Mr. Cowell said. “I’d love to find a Taylor Swift, somebody’s who’s relevant, rather than just a contest winner.”

It was characteristic Cowell straight talk, but also an implicit swipe at one of the problems facing “Idol” at the beginning of its twilight: its apparent inability to mint longstanding stars. Only two of the eight “Idol” winners,Kelly Clarkson and Carrie Underwood, have sustained long careers after kicking off the “Idol” training wheels. The show remains the gold standard for television juggernauts, but as talent scouting goes, it’s about average.

Tonight is the true beginning of this season’s competition, following several weeks of audition rounds, and again, the show’s star-making potential is in doubt. The “Idol” dream of finding pop generalists fell by the wayside a few seasons ago. Now it’s more comfortable than ever with genre singers, ones with specific, even narrow identities. Quirk is as likely a route to fame as versatility, and probably a more expedient one.

Of the 24 semifinalists — back to the show’s normal number, down from 36 last year — several stand in a personal niche. Early favorites include two women, Haeley Vaughn, a teenage, black pop-country singer, and Crystal Bowersox, a husky-voiced folkie in the Indigo Girls vein. Lilly Scott is an eccentric jazzbo and John Park a clean-cut standards crooner. Even Tim Urban, the last-minute replacement for the disqualified semifinalist Chris Golightly (reportedly for having a recording contract), seems to have been molded by listening to latter-day pop emo bands.

Any of these paths can end in pop success, but the most plainly relevant contestant this season is Andrew Garcia, a YouTube-era star in the making, one of thousands of people who for the last few years have in essence been playing “American Idol: The Home Game,” posting clips of their cover-song performances to the Internet in hopes they’d get noticed. In those clips, which still pepper YouTube, he’s a clear adept, able to breezily disassemble and reformat popular songs for his limited vocal range — a recipe for modern “Idol” success. His version of Paula Abdul’s hit “Straight Up” during Hollywood week has been this season’s most memorable and thoughtful performance by far.

“Idol” might make Mr. Garcia a star, but he’s done most of the heavy lifting already, a seasoned competitor on a show that prizes inventive revisions of pop standards. Mr. Garcia may not have a record deal, but in this regard, he’s no amateur.

If the outcome of this season has felt a bit like a fait accompli, more surprising to watch have been the shifting dynamics at the judge’s table.

Last season, the songwriter Kara DioGuardi was brought on as a fourth judge, joining what had seemed like an impregnable trio: Mr. Cowell, Ms. Abdul and Randy Jackson. Ms. Abdul departed after last season, and her chair on the judging panel has been filled by the talk show host, actress and comedian Ellen DeGeneres, who signed a five-year contract to appear on “Idol.”

It must have been maddening for Ms. DeGeneres to have suffered the media swell that represented and assessed her as the new Ms. Abdul, when all along she probably understood that she was in fact the new Mr. Cowell.

“My role on the show is somebody who’s run a successful record label,” Mr. Cowell said during last week’s conference call. But he’s also the reliable center of sanity — before Ms. DioGuardi was added to the panel, often he was the only person tethering the show’s judging to logic. Ms. Abdul was a shapeless blob of warm feeling, and Mr. Jackson is value-neutral, an uninterrupted stream of small words and big emphasis.

With Mr. Cowell moving out of the picture, Ms. DeGeneres is free to pick up his mantle, meaning the person who fills his chair next season — if indeed someone does — can be looser and less predictable. Ms. DeGeneres, heir apparent to Oprah Winfrey, has more clout than most record executives, or for that matter most record labels.

So beginning now, while Mr. Cowell is in his lame-duck phase, “Idol” is becoming Ms. DeGeneres’s ship to steer. And if the Hollywood round was any indication, she’s plenty able. She was articulate and humorous, withering when she needed to be and completely polished in her casualness, the product of more than two decades of television experience.

Made most vulnerable by Ms. DeGeneres’s arrival is Ms. DioGuardi, who when she joined the show immediately became the second most sensible member of the judging panel, and sometimes the first. But so far this season, Ms. DioGuardi has been recast as, variously, a buffoon, a tart, an emotionally tone-deaf den mother. Her awkward and disempowering scenes with celebrity guest judges during the early audition rounds, particularly with Katy Perry, were difficult to stomach, with Ms. DioGuardi seeming to be a foreigner on her own show.

When the lanky blues-rock singer Casey James auditioned, she and Victoria Beckhamsuggested he take his shirt off, which he did. When he made it to the Top 24, she hugged him and kicked her leg up behind her, for which the other judges teased her mercilessly.

Last week the judges informed contestants, one by one, whether they’d made the Top 24. When Angela Martin came to learn her fate, Ms. DioGuardi broke the news to her, clumsily sitting on Ms. Martin’s chair, pushing her onto the armrest, in the process of telling her she’d been cut. Ms. Martin, who is too old to audition for “Idol” next year and whose ambitions to make the show have been complicated by a series of personal difficulties, was crestfallen.

Her faith in Mr. Cowell was not quite shaken, though. Last week, she told People.com, “I tell anyone I meet I am going to go on ‘The X Factor.’ ”

Or perhaps not. Ms. DeGeneres invited Ms. Martin onto her talk show, where she performed and was told that Ms. DioGuardi was going to write a song for her to record. Ms. DeGeneres also promised to secure Ms. Martin a record deal. The new “Idol” team was closing ranks around a new godfather in the making.