Last Thursday, on his second night back at work, Jay Leno looked into the camera and offered this obviously unscripted joke: "This is the loosest the show has ever been. We want the writers to win this damn thing so we can get back to the boring, old Tonight Show."

Why Leno would want to get back to his typically dreary, middle-of-the-road show is beyond me, especially given his performance last Wednesday, Thursday and Friday. He was, indeed, loose, funny, edgy -- basically the guy audiences loved as a guest on the old Late Night with David Letterman show.

For at least three nights, Leno didn't need writers. His monologue jokes were sharp (like comedy-club Leno rather than inoffensive, Tonight Show Leno), his comedy bits solid (did you see his announcer, John Melendez, model the "mankini"? Revolting, but funny). Even his interviews were entertaining. He was particularly engaged and engaging with Republican presidential candidate Mike Huckabee, who's a much better talk-show guest than potential leader of the free world.

Leno didn't have any A-list guests last week, but it hardly mattered. "The hard part is, it's going to be hard getting guests," he said. "The good part is, when the movie is crappy, we can say it was crappy." How refreshing.

Unfortunately for the striking writers, neither Leno nor any of the other late-night shows that went back to work last week helped their cause. Late Night with Conan O'Brien was fresher, funnier and weirder than usual, and Jimmy Kimmel Live, which always has the air of a show that's being made up as it goes along, didn't miss a beat.

O'Brien had the single best sketch of the short week -- he'd spring up on tour groups that came through his dark studio and put on a mini-show -- and Kimmel was great with the rapper/actor Ice Cube. Kimmel is the only late-night host to give serious attention to rappers, so they let him have his fun. Ice Cube came onstage to his song "Gangsta Rap Made Me Do It," a track that someone leaked well in advance of his next album. That prompted Kimmel to ask, "Shouldn't you, as Ice Cube, kill them?" When Cube said, "You can't really pinpoint who did it," Kimmel responded, "Well, kill everybody."

With unscripted lines like that, who needs writers?

Meanwhile, the results were mixed at the two shows that were able to make deals to bring their writers back, The Late Show with David Letterman and The Late Late Show with Craig Ferguson. Ferguson's show followed its usual formula -- terrific monologues made that much better by the host's cheeky delivery, marginal comedy bits with zero production values that Ferguson improves by laughing and winking his way through them, and snooze-inducing interviews. (Huckabee was a mediocre guest on Ferguson's show.)

Letterman, though, was shockingly off his game. Instead of roaring back with A-list guests and sharp material, his performance was lethargic and, except for Robin Williams, his guests inconsequential. His writers were no better, sending him out with "last-night's-audience-was-so-bad" jokes, lame Top 10 lists and segments where he interviewed Late Show staff members. While Leno came out his first night back and took real questions from real audience members -- and gave quick, funny answers -- Letterman gave dull answers to people posing as audience members.

His low point was Thursday night with comedian Bill Maher and Ellen Page as guests. He's never been a great interviewer, but wow, was he disengaged. (He more or less avoided politics with Maher and he asked almost nothing about Page's new hit movie, Juno.) Maher fared better on O’Brien's show.

Letterman's bad habit of sucking up to guests (last week, it was Donald Trump) and non-guests (Rosie O'Donnell, who apparently is reeling from a joke he made about her needing to shave her back) continued in earnest. And he even seemed to pull his punches when criticizing the producers who are keeping the writers walking the picket lines.

The old Dave would have been railing against the pinhead producers by name. This Dave makes jokes about what AMPTP, the producers' organization, stands for. (It's Alliance of Motion Picture and Television Producers, in case anyone cares.)

All five late-night hosts took great pains to say they support the striking writers. And it's possible that as the strike continues, the late-night hosts who don't have writers will wear out. But for the first week, at least, the return of late-night TV did the writers no favors.

Looks like it's going to be the dramas and comedies -- shows that can't possibly exist without writers -- that force an end to the strike.