If you’re ever asked what you think of an unfamiliar comedian or TV comedy, there’s a simple answer that will always make you sound smart: “I think the earlier stuff was better.” Cliched or not, the sentiment is true too often and perhaps best exemplified by television’s premiere comedy lineup: NBC Thursday nights.

The four NBC Thursday-night comedies — each halfway through the 20+ episode season — can be broken into two clear groups: new and old. “Parks and Recreation” and “Community” are essentially in their first season (“Parks” had a tepid six-episode first season last spring), while now-classics “30 Rock” and “The Office” are in their fourth and sixth season respectively.

“Parks and Recreation” has quickly established itself as the best comedy on television — providing the “Seinfeld”-esque relatability of “Modern Family” with the brilliant (but elitist) wit of “Arrested Development.” Amy Poehler stars as the endearingly hapless, yet sneakily competent Leslie Knope, a director of the parks and recreation department in a highly bureaucratic small-town government. In the short first season, Knope was simply a watered-down version of Michael Scott, Steve Carrell’s character in “The Office.” But right from the start of season two, Knope (who’s ideal man has the brains of George Clooney in the body of Joe Biden) has become perhaps the most nuanced, loveable character on TV.

Buoyed by Knope’s charm, the supporting cast has blossomed as well, propelling incredibly unique (and hilarious) love stories. Aziz Ansari (who, of course, is headlining tomorrow’s Winter Show) plays the crass, warm-hearted Tom Haverford, who is secretly pining over his too-hot Canadian wife, who married him so she could stay in the country. The burgeoning romance between Andy (Chris Pratt) and April (Aubrey Plaza) is utterly delightful, as well, as clueless airhead Andy (“Anything is a toy if you play with it”) charms the snarkily cynical April. It’s the kind of romance that would be too grounded (and thus relatable) for “30 Rock” and too whimsical for “The Office.”

As “Parks” creatively thrives, so does fellow newcomer “Community,” although it hasn’t quite found its tone yet. Sometimes the ever quotable one-liners are better suited for a David Letterman monologue than situation comedy (“To me, religion is like Paul Rudd. I see the appeal, and I wouldn’t take it away from anyone, but I also would never stand in line for it”). Nobody in real life speaks like the characters in “Community,” but the world would be a much funnier place if they did.

“Community” follows a band of six community college students who come from vastly different backgrounds. Joel McHale (of lazy Sunday staple, “The Soup”) stars as Jeff Winger, once hotshot lawyer, now jaded student. The show is a true ensemble — it’s rare to find chemistry as potent as that between Abed and Troy or Jeff and Pierce (Chevy Chase). But while the dialogue snaps and the relationships make you smile, the show has yet to establish any sort of stakes or reality. Jeff and Annie hook up for one episode with no consequence, grades move the plot forward but don’t really matter and there’s little continuity in the classes they’re taking (one week Annie’s working in a psych lab, the next she’s on the debate team, the next she’s a journalist). “Community” clearly has an absurdly talented team of writers — they just need to learn to translate their comedic chops into a more understated sense of reality.

With “Parks” and “Community,” every episode is a revelation. Episodes of “Parks” show us Leslie’s (“Hoarders”-worthy) house for the first time, providing fresh insight on the characters, while “Community” is still only beginning to explore the show’s central romance between Jeff and Britta. This is sharply contrasted with the increasingly stale repetition of their Thursday night companions.

“30 Rock” and “The Office” have both earned their place (alongside “Arrested Development,” “The Comeback” and, frankly, “The Hills”) among the best modern American sitcoms, yet both shows lack a certain oomph this season. The gags and the quips are clever as ever, but the situations feel stale. Whereas each episode of “Community” reveals new facets of the characters, “The Office” has weird standalone episodes about Michael’s mishaps with a group of third graders 10 years ago. Whereas “Parks” uses big-name guest stars like Justin Theroux to show how Leslie handles the excitement of a new relationship, “30 Rock” uses Julianne Moore to allow Alec Baldwin to break into houses and spew dated jokes about Facebook.

“The Office” has remained fresh for years through its willingness to completely revitalize its premise. Last season, Michael, Pam and Ryan broke off from Dunder Mifflin to start a new company, and the show felt young again. This season, both “30 Rock” and “The Office” have missed opportunities to refresh and revamp. “30 Rock” explored Liz Lemon’s nascent fame thanks to a best-selling book. Episode seven focused on Liz’s attempt to start a spin-off talkshow called “Dealbreakers.” Instead of allowing the show to spin off in this new direction (which would completely transform Liz’s character), the writers killed off the story in one inconsistent, annoying episode. Similarly, “The Office” misguidedly ended its bankruptcy storyline in the Christmas episode.

Both shows are at their best at their freshest. This season of “The Office” has only been notable for the emergence of Erin Hannon, the new secretary, who stars in the revelatory “Subtle Sexuality” webisodes (www.subtlesexuality.com) and has a romance brewing with Andy that harkens back to the early days of Jim and Pam. “30 Rock” is self-aware about its predicament — the season premiere had the meta title “Season 4,” as Liz tries to find new talent for TGS that will appeal to Middle America. It’s frustrating to realize that the team behind “30 Rock” is aware of the problem, yet refuses to find a solution. The only new character this season is the hopelessly boring Danny (Cheyenne Jackson).

As they enter the second half of the season, “30 Rock” and “Office” need to look to their Thursday night companions for inspiration. Otherwise, they will end up as tired as a “that’s what she said” joke.