Naomi’s woes are good medicine

Audra McDonald spent most of the first season of “Private Practice” seemingly steeling herself -- against criticism about her 11th-hour, post-pilot replacement of Merrin Dungey in the role of Naomi Bennett; against the inanities of the show’s scripts, which demanded glibness more often than reflection; and, on-screen, against the very possibility of feeling.

As Naomi, she was rigorously firm, almost dispassionate. As people bed-hopped and were emotionally flimsy around her, she remained stern at the center: only intermittently moved by her husband, Sam (Taye Diggs); unswayed by the advances of Dell (Chris Lowell), the young office assistant who pledged to be the rock for her that she was for everyone else. McDonald is a strong, vivid actress, but such gravity felt at odds with the breezy tone of “Private Practice.” Often, McDonald looked as if she might like to be on another show altogether -- something on PBS maybe.

Problem was, the tougher Naomi became, the lighter Addison (Kate Walsh) had to be to keep the show’s balance. As Naomi retreated more into herself, Addison was increasingly flighty -- her romantic quandaries lacked depth, and her personal aimlessness spilled over into the professional, the realm in which she was supposed to be the most certain.

As a result, “Private Practice” regularly felt unmoored and became something of a critical punching bag. Redeeming the show required, at least in part, recalibrating Naomi so that Addison could find her footing once more, and the second-season premiere (ABC, 9 p.m. Wednesday) is designed to that end. At the beginning of the episode, the only conversation she’s willing to have is with her dessert plate. She’s burying her anxieties -- about the financial troubles of the practice, about her relationship with Sam -- in an unending stream of sweets. Addison, meanwhile, is shopping for handbags. “I am having sex,” she purrs, “with Bottega Veneta.” (Here’s to the softness of woven leather.)

But about 15 minutes in, the episode lands in the hard grip of something this show has too often skirted past: a genuine medical drama. Naomi has consented to help a family with a leukemia-afflicted child by helping them conceive a baby; the umbilical cord blood can save the sick child’s life. But things go awry, as they do, forcing Addison to do what she does best (practice obstetrics) and heretofore has done poorly (moralize, be serious). Her indignation, both toward the patient and with Naomi’s ethically sketchy doctoring, is intense and acts as an instant corrective to the show’s narrative wanderlust.

Oversexed tendencies notwithstanding, the show’s most alluring and enticing moments come not when Addison is swooning over the police officer who appears to be genially stalking her or deciding whether to swoon over fellow doc Pete Wilder (Tim Daly) but when she finds her professional compass. “I put my hands inside a woman’s body, and I fix what’s wrong,” Addison says as part of an ad campaign for the practice, sounding like a mystic healer.

And Addison’s rebirth coincides neatly with the impending collapse of Naomi. Toward the end of the episode, there is a brief scene in which she, beleaguered and on her last leg, utterly melts into Sam. In those 15 seconds, McDonald’s genius as an actress is clear, communicating with just a few facial movements and shading of the eyes a world of hurt and letdown.

(McDonald also forces something weighty from Diggs, who is fighting his handsomeness at every turn.) And later in the episode, when she thinks things are falling back into place, her soft, knowing, warm smile is one of the show’s greatest victories, even though it comes just before everything goes wrong once again.