Like a willow, I can bend. In the video for “Stand Back,” Stevie Nicks, at the mic stand, arches her spine and rears back her head as she croaks this line. Although she may be referring to her flexibility in relationships, it’s not difficult to imagine her producers having different thoughts. One of the problems facing any producer of a Stevie Nicks tune has been the singer’s versatility, her willingness, over the years, to assume a number of different musical personae: ’60s folkie (the Buckingham/Nicks album, “Landslide), country crooner (“That’s Alright,” “Farmer’s Daughter”), screaming rocker in the Janis Joplin mold (the live version of “Rhiannon,” “Stop Draggin’ My Heart Around”); ethereal pop chanteuse (“Sara,” “Gold Dust Woman”); composer of odd novelty tunes (“Fireflies,” “Blue Lamp”); Top 40 hitmaker, drowning not in a “sea of love,” but in a wash of synths (“Stand Back,” “Talk to Me”). What to do with that marvelous, amenable voice? Most of Nicks’ producers have thought about it way too much.

Lindsay Buckingham has said that he had no idea how distinctive Nicks’ voice was until he was no longer singing beside her, and for this reason, he was her best collaborator, shaping Nicks’ amorphous material (compare her original, labored version of “I Don’t Want to Know” with Buckingham’s kickier rendition on Rumours) into unblemished pop-rock gems. Uncowed by that unique voice and persona, Buckingham concentrated on songcraft, allowing Nicks to just be. On Trouble in Shangri-La, Nicks’ voice occasionally takes on a heavy, less girlish, Marianne Faithfull growl, as on “Every Day.” She now has the world-weary, crackled voice of a woman. But Nicks is ill served by her producers, including Sheryl Crow, who helps out with five of the 13 tracks. Chris Lord-Alge, staring out from the liner notes’ group photo like Svengali, gives each track a uniform sheen, making all the songs, in Nicks’ words, “into one entity.” (See “homogenous” for synonyms.)

Nicks’ final incarnation seems to be that of the MOR, VH1, easy-listening station staple. We’ve seen it happen before to rock goddesses: It was not as far from the “Nutbush City Limits” to the “Typical Male” as Tina Turner’s fans might have liked. Nicks, who once sang of Gypsies and Fireflies and Dreams and Sleeping Angels and Dragons and Sisters of the Moon and Storms and Nightbirds, now sings songs with titles like “Love Is,” “Love Changes,” and “It’s Only Love.” Can a Grammy nomination be far behind?

Instructively, “Sorcerer,” one of the livelier tunes here, is a leftover from her Fleetwood Mac days (three of the tunes on this album were written in the ’70s), and reflects the former coked-out lyric writing that drove Buckingham batty (“Sorcerer/Who is the master/A man and woman on a star stream/In the middle of a snow dream”). The guitar opening to “Planets of the Universe” (another of the ’70s tunes) is also close enough to the unmistakable “Rhiannon” guitar riff to cause listener whiplash. The rumored Fleetwood Mac studio album can’t come too soon.