Speaking of alternate universes, after three episodes of NBC’s “Parenthood” I’m still finding it hard to watch any scene with Lauren Graham and not think of how Maura Tierney would have played it, had she not had to bow out of the series because of cancer.

It’s more than distracting — it’s almost certainly affecting my overall feelings about the show in a negative way. And I don’t mean that as a criticism of Graham. It’s just that Tierney is such a forceful, edgy presence (as was the case in the original, unaired pilot shown to the press last summer) that the lightness Graham brings to the role seems almost frivolous — even when she’s upset about something. When Graham’s Sarah Braverman can’t find a job or fights with her daughter, I just feel that however much it affects her, it would affect Tierney’s Sarah more profoundly.

In general, watching “Parenthood” is a bit of a bipolar experience. I bow to no one in my admiration for showrunner Jason Katims, the genius behind “Friday Night Lights,” but frankly, “Parenthood” is to “Lights” as Graham is to Tierney. It’s just softer and less compelling.

Storylines that would he handled with nuance on “Lights” are much more on the nose in “Parenthood.” Example: Two weeks in a row, “Parenthood” has given us scenes of other parents staring daggers at Erika Christensen’s thanklessly besieged Julia. Each time it was awfully heavy-handed, let alone how it felt to see it in back-to-back episodes.

Ramos But to continue the yin-yang theme, just when I’m ready to give up on “Parenthood,” the show will give me a scene with a line of dialogue or an approach that feels entirely fresh. Craig T. Nelson, who himself suffered from coming on more than a bit too strong in the show’s premiere, had a wonderfully nuanced moment when he copped to the marital problems he’s been having with wife Camille (Bonnie Bedelia). And Graham, to her credit, provided a great sounding board. I’ve also liked the way “Parenthood” has rescued Sarah Ramos (pictured) from her robotic performance as the younger sister on former NBC family drama “American Dreams” and let her show how much life she has as an actress.

By the way, I’m not at all ignorant of the fact that after the ratings struggles of “Lights,” on-the-nose moments and lighter performances might be exactly what Katims and “Parenthood” are going for. But it’s not as if “Parenthood” is knocking it out of the park in the ratings, so if there are choices being made, count one viewer who’d like to see the show err on the side of brilliant subtlety.