Oh, dear. Three weeks in, 2 Broke Girls is not quite living up to its potential as the new season’s break-out/talent-filled/girl-power-trend sitcom. I’m not talking about ratings — those are solid, for sure. I mean the actual quality of the jokes and the direction (or lack of one) the series is taking as it settles in as a weekly series.

Now that we’re beyond the meet-cute, Laverne & Shirley with sex jokes set up that brought Kat Dennings’ Max and Beth Behrs’ Caroline together in a somehow cramped yet roomy Brooklyn apartment, 2 Broke Girls needed to do two things: move that relationship along and develop some of the supporting cast. But three weeks in, about all we’ve got is Max bonding well with Caroline’s horse, Chestnut.

Sure, we still have Dennings’ fine line-readings. This week, I enjoyed her drop-dead deadpan delivery of, “I did not light up. There is no light in me.” And Behrs is, through the sheer will-power she seems to bring to bear on the inflection she gives her rich-girl prattle, managing to make her one-dimensional character more vivid. Her Caroline is now a pleasant combination of spoiled, self-conscious about being spoiled, and a good sport at playing straight-woman to set up Max’s drolleries.

But 2 Broke Girls does that mediocre-sitcom thing of having its actors deliver lines as though they were jokes but which, upon cursory inspection, prove not to be. “I’m eight dollars,” said Caroline, looking at a pair of $800 shoes she used to own, now marked down at the Goodwill center where Max brought her to shop. “I’ve been reduced.” The studio audience laughed… at what? Yes, there was a little poignancy in the line, but not mirth. Yes, there was a pun there, but not enough of one to elicit those suspiciously hearty guffaws.

Some further danger signs for the series:

• A limp variation on the old hide-the-salami. The diner cook Oleg used the too-often punned meat as a punchline this week.

• The repeated use of the word “bitch” as though it is inherently funny. Just calling someone a “bitch,” without any real joke construction surrounding it, fails to work as humor.

• The portrayal of Max and Caroline’s Asian boss. Han Lee’s flustered response to seeing up Caroline’s skirt last week — “So sorry but many thanks” — was only two consonants away from Joe Jitsu’s “So solly” stereotype in the old Dick Tracy cartoon series.

2 Broke Girls was the Whitney Cummings sitcom that was supposed to be the diamond compared to the rough that is NBC’s Whitney. What is holding Broke Girls back? Is it the hovering presence of co-producer Michael Patrick King, who wrote the second episode and doesn’t seem to have adjusted the vulgarity level to the right setting? (Sample line last week, after Caroline asked Max to open the apartment’s back door: “We’ve only known each other for two days and already you’re asking for back door?” Is that a left-over from, say, fifth-season Sex and the City Samantha?)

The hand of Cummings could still be descried this week when a bartender served the two broke girls drinks, then went over to a couple of male patrons and high-fived them, yelling, “Vagina!” Cummings is, after all, the woman who recently told The New York Times, “Vagina jokes paid for my house.”

Yes, but when she used them her stand-up act, they used to be funny ones.

I’ll keep rooting for you, though, 2 Broke Girls! You had such promise. Let’s shape up and give this half-hour a bit more snap, shall we?

Twitter: @kentucker