The trouble isn’t really that theater is in decline. Rather, we seem to have found a very wide plateau on which to level out. The stripe of mediocrity is wide, and for anyone who has worked in a literary office within a theater, the reasons are obvious. With so many scripts, and so few flashes of genius, complexity and audaciousness rarely make it through the gristmill of development. Instead, we have a thousand pieces that all debut on that predictable plateau – not wonderful, but adequate enough.

Cheryl L. West’s “Birdie Blue,” now at Second Stage, roosts on that plateau. Three things elevate it above its fellows: a willingness to be chronologically bewildering, a bushel of snappy Southern comebacks, and an intense romantic connection between, ah, people of age. A few pluses do not, however, add up to much of a play. S. Epatha Merkerson, a household face from the “Law & Order” franchise, sasses and smooches and smacks her loved ones with respectable energy. When she waltzes with her husband, Jackson, (Charles Weldon), she even seems to be relaxing into something like a real performance. But Ms. West’s play then whirls her into another scene-let, another mini-portrait of a difficult life, and her rhythm is lost again.

Birdie’s story, and this is not a compliment, has a whiff of life’s actual messy structure about it. We meet her as an old woman, readying for a trip – and her list has a number of mysterious items to check off. Her husband, reduced by disease to a nearly infantile state, has to be lashed to his bed, and a cake she is baking for her son seems doomed to go uneaten. Flashbacks introduce us to the son, Bam, at various ages, a few of her siblings, and a neighborhood child who takes refuge in Birdie’s house (all played by Billy Porter). Boundaries between characters and times elide, since all times have begun to collide in Birdie’s mind (a stage direction calls this her “house of the mind”).

Though Ms. West begins by tossing us into Birdie’s haphazard reminiscences, she eventually caves in to narrative pressure. Birdie addresses her audience directly, making connections for us, and the chronology settles down into a rather conventional “life.” As a kind of thematic anchor, we hear the news coverage of Martin Luther King Jr.’s assassination. That great loss follows Birdie as she loses many things, from a son who rejects her to her beloved Jackson’s mind. Ms. West avoids giving Birdie wings or a halo; our heroine slaps her son, nearly whips her demented husband, and reacts with rage when Dr. King would tell her to love. The piece achieves a richness and difficulty of character, but then falls prey to shabby plotting and sappy mottos (never abandon your dreams; love can surprise the most hopeless heart).

Unfortunately, the production saws heavily on those very sentimental strings. Both literally (sound designer Obadiah Eaves puts portentous cello thrums under everything) and in Seret Scott’s direction, the humor of the script always gives way to mawkishness. Ms. West and the actors indulge in some deliciously homespun bons mots (“Swear some old woman done rented my body out and didn’t even bother to pay me rent,” complains Birdie). These turns of phrase are verbal music, and in a production that equates music with love, the lilt of Birdie’s voice is important underscoring. When he does sing, Mr. Weldon’s Jackson seduces more than just his bride – he shuffles off with our hearts in his hand. But Mr. Porter, though he looks great in drag, had nearly no voice during previews.

For both star and playwright, as much as it pains a fan of experimentalism to say it, the best moments are the most naturalistic ones. Ms. Merkerson, given time and interaction with the excellent Mr. Weldon, hints at a deeper, stronger play underneath the one we are watching. And Ms.West (not helped by Ms. Scott’s direction) fumbles worst when things are at their most “magical.” Some blame must land with set designer Anna Louizos, who falls back on twinkling lights to show us heaven’s gate. But for everyone concerned, “Birdie Blue” soars highest the closer they stick to the ground.

(307 W. 43rd Street at Eighth Avenue, 212-246-4422).