Even the top TV creators have the occasional strikeout to go with their hits.

For Steven Bochco, who gave TV viewers such classics as “Hill Street Blues” and “NYPD Blue,” there was last season’s “Public Morals” and “Total Security.” (You blinked, you missed ’em.).

David Angell, Peter Casey and David Lee, creators of the urbanely witty “Frasier,” have turned around this season and generated the comedic implosion “Encore! Encore!” (No, please, no more!).

John Wells has created two great dramas, the immensely popular “ER” and the criminally short-lived “China Beach.” That’s what makes his new “Trinity” something of a disappointment.

The family drama, premiering at 9 p.m. Friday on NBC, would probably score higher if it had come from a lesser-known talent. But with Wells as executive producer, the bar automatically gets raised, and “Trinity” just can’t clear it (yet anyway).

“Trinity,” set in Manhattan’s Hell’s Kitchen, tells the story of the extended McCallister clan. The father owns a bar, and the mother is a homemaker; the children are a cop, a union organizer, a priest, a Wall Street executive and an alcoholic. It’s a good thing the Irish aren’t overly sensitive about political correctness.

The emphasis of “Trinity” is family interaction, soap-opera style. Cop Bobby (Justin Louis) is down on union-organizer brother Liam (Sam Trammell) for sticking with his mob-linked boss. Substance-abuser Amanda (Bonnie Root) is constantly seeking help from her priest brother Kevin (Tate Donovan of “Friends”). Capitalist Fiona (Charlotte Ross, “Days of Our Lives”) comes crying to her mother, Eileen (Jill Clayburgh), after her married lover goes back to his wife. Then there’s the mysterious death, years ago, of another brother, which Bobby wants to investigate against the wishes of his father, Simon (John Spencer of “L.A. Law”).

There are lots of little entanglements, and all the McCallisters simmer just beneath the surface, with an occasional flareup. But overall, “Trinity” is just plain draggy, and lacks much action of any type. An injection of humor wouldn’t hurt either.

Based on reputation alone, Wells will receive the time he needs to get “Trinity” up and running more smoothly. Since it’s the only straight drama in its time slot, and it pairs well with the moody “Homicide” which follows it, “Trinity” stands a good chance of surviving and maybe thriving. The McCallister house may yet become a less gloomy place to visit.