Oh, that Paloma Herrera.

No dancer can maintain the same level at every performance, but Ms. Herrera is distressingly erratic. Her problems lie not with technique, but in matters of style and articulation. Having performed a sensuous and eloquent Terpsichore in “Apollo” at American Ballet Theatre’s gala Monday, she slid back into a lot of bad old habits during Tuesday night’s “Le Corsaire.”

In this swashbuckling specimen of ballet buffa, Ms. Herrera danced Medora, a maiden captured by slave traders but rescued by her pirate lover, Conrad. I liked Ms. Herrera’s emulation of Galina Ulanova’s legendary run in her exit after the brief abduction scene in which Medora is introduced, but when she began to leap soon after that, her leaden back leg told me that she was out of sorts. She remained so for the entire evening.

Her arabesques were abrupt. Her acting was mechanical and much less interesting than her Medora last year. Her demeanor was sometimes downright smirky, especially in the Act III dream sequence, the “Jardin Anime,” where she needed to be serene and triumphant. Her fouette turns in the coda of the Act II pas de trois began notably; her weight was buoyantly lifted, whereas she sometimes has the tendency to fold in on herself. But when she unwisely began to fire off double fouettes, they discombobulated her. (At least she didn’t try triples.)

Putting Ms. Herrera next to Xiomara Reyes, who danced the second lead, Gulnare, wasn’t a good idea, since they enable each other’s worst and most coarse proclivities. Ms. Reyes isn’t one to hide her coquette wiles under a bushel. Perhaps they were cast together simply because last night was a theme evening – “Noche Latina” – celebrating the influence of Spanish and Latin-American dancers at ABT.

It was intriguing to see Ms. Reyes take the Act I “Pas D’Esclave” terribly seriously as a dramatic pretext. Gulnare is dancing a pas de deux with her exploiter, the slave dealer Lankedem, and Ms. Reyes went all the way to suggest a victimized Puccini heroine. That worked out nicely.

But when Ms. Reyes came to the harem shenanigans of Act III, her archly inclined head tilts and incessant oiellades were laid on with a trowel. After her curtain call following her “Jardin Anime” solo, Ms. Reyes skipped offstage a la Cupid in “Don Quixote.”That pretty much said it all.

Angel Corella delivered a middling performance as the slave Ali. By now, the role seems to rattle him terribly. It may be that because he dances only in Act II, he feels under undue pressure to mow down the audience; he may feel by now that he must top himself. In any case, his pirouettes were so fast and furious that they became a blur, but in other aspects he was relatively muted. He didn’t introduce any new stunt variations. He even scanted his corkscrew pirouettes of old. Rather than stuntsmanship, however, Mr. Corella would benefit from a new approach to a role that mandates he simply dance beautifully.

This “Corsaire” served as a valedictory performance by Julio Bocca, who is retiring this year. Almost from the beginning of his career, he has overscheduled himself so recklessly that it is astounding he is still on his toes. His body is visibly traumatized, and yet he went for broke and gave an extraordinary performance as the pirate hero Conrad. Autocratic, at times nearly wild-eyed, his temperamental flour ishes seemed like a quintessential representation of the 19th-century Romantic temperament – at its inception 150 years ago, “Le Corsaire” was suggested by a poem of Byron’s. At the same time, Mr. Bocca’s technical execution was often meticulous; he showed a way to broker academic integrity and temperamental sizzle that any dancer could study to his profit.

Jose Manuel Carreno, as Lankedem, and Herman Cornejo, as Conrad’s perfidious lieutenant Birbanto, were also first-rate. Some of the evening’s best dancing came from the three odalisques of Act I, Stella Abrera, Maria Riccetto, and Veronika Part, each of whom scintillated in her solo.

Until July 15 at the Metropolitan Opera House (Lincoln Center, 362-6000).