There’s only one reason to see Stephen Schwartz’s “Wicked,” and it isn’t the plot, choreography, lyrics or cast. The Fabulous Fox Theatre’s current run (through Sunday, Jan. 6) of the Broadway blockbuster is carried by Carmen Cusack’s singing voice. Without it, the musical is nothing but an average evening at the theater.

The adaptation of Gregory Maguire’s 1995 novel has become a musical sensation-even showing at the Fox in 2005-but it was difficult to pinpoint why after the Thursday, Dec. 13, performance. The lyrics were unintelligible, hidden beneath a layer of orchestral overload and the ensemble’s garbled voices. It is a shame, especially since Cusack’s soaring and confident voice is the musical’s strongest asset.

The story of Oz’s witches focuses on the relationship between Elphaba (Cusack), the future Wicked Witch of the West, and Glinda (Katie Rose Clarke), the future Good Witch of the North-two characters from L. Frank Baum’s beloved The Wizard of Oz. The initial enemies become friends when they room together at school, but they are eventually separated by their differing views about what is most important in life: thriving socially or standing up for what you believe in. At least they weren’t bickering about dirty laundry on the floor or late-night visits from boys.

The music was flawlessly performed, and no lines were noticeably stumbled over, yet I was less than entertained by the evening’s performance. I frequently found myself thinking about other things-not exactly what one expects from a Grammy- and Tony- winning musical. My ears and eyes perked up only when Cusack took center stage; she is particularly affecting in “Defying Gravity.”

Clarke finally comes into character with the perky tune “Popular,” in which she uses Glinda’s airheaded tendencies to amuse the audience. Cliffton Hall’s portrayal of Fiyero, over whom Elphaba and Glinda come to odds, is unfortunately less than charismatic. The dull, lackluster Hall couldn’t charm even the most romance-deprived lady.

Though “Wicked” helps us understand the background of the despised green witch, and perhaps even garners her some sympathy, a viewing of the musical at the Fox may only confuse you as to why the show has collected so many awards. Perhaps the wizard and his magic have something to do with it.