It’s in the full-length ballets that Diana Vishneva offers gifts no other ballerina today can claim. In Giselle, Swan Lake and Romeo and Juliet, this star of the Kirov and of American Ballet Theatre brings her heroine’s imagined past and looming future to bear on the steps. She bends the drama to her – and deepens it in the process. But for Vishneva to work her magic, the story must already be deep.

Diana Vishneva and Jared Matthews in Sylvia

Frederick Ashton’s delightful Sylvia is only deep in spots. A god, Cupid; a goddess, Diana; a dopey shepherd; and an Ali Baba-esque villain turn the crank of its mechanical plot to send our heroine, Sylvia – a chaste and brawny nymph – flying from act to act.

Sylvia is a warmly comic compendium of ballet genres: 18th-century Neoclassicism, home to naiads, satyrs, shepherds and the whole pantheon of Greek gods; wickedly erotic Orientalism; and the radiant academic style of The Sleeping Beauty. Vishneva must do the opposite of what she’s famous for: not develop a through-line of motivation but display an almost vaudevillian versatility.

And did she – in her debut outing on Wednesday, opposite Ethan Stiefel as the shepherd? Yes. Admirably.

Her Sylvia starts out strong, abrupt and certain, pumping her fist in the air like it’s 1969 and she’s just joined the Black Power Movement. But even before Love pierces her, something in her shifts. As she wrestles with the besotted shepherd beseeching her to give him a chance, her steps grow gluey and her back more pliant, as if she were softening herself for Cupid’s wound.

Vishneva has a harder time with Act Two, Ashton’s affectionate take on the exotic-erotic ballet. She can be sexy and she can be funny, but to be funny about being sexy, as when Sylvia dresses up in harem-wear to lure her brutish captor to drink, she needs to sharpen her timing and embolden her moves.

In Sylvia this season, everyone does. The ballet has lost some crucial brightness since its 2005 ABT premiere. But this always seems to be the problem when ballet performances fall short. Dancers often confuse a bland smoothness with refinement – and, by extension, with ballet itself. This portmanteau ballet could prove just the antidote, if it were better-coached.

As for Vishneva, her powers of imagination recover in the final act, where she enters the shadowless world of happy endings with pizzicato pluck. ★★★☆☆