In relation to its own impressive previous showings here, the Houston Ballet appeared to be backpedaling last night as it opened the new ballet season at the Kennedy Center Opera House with a disappointing mixed bill.

The troupe has no need to prove itself a worthy classical outfit, having long since done that here and elsewhere. The Houston Ballet's growth over the past decade, under the artistic stewardship of Ben Stevenson, has been little short of phenomenal. With an annual budget of more than $7 million, close to 50 dancers and a luxurious new home base in Houston (new studios and the recently launched Wortham Theater), the company ranks among the nation's largest and most fully developed ballet organizations.

In its two most recent visits to the Washington area, the troupe also displayed some strong sides of its mostly conventional repertory. At Kennedy Center in the winter of 1986 we saw the company's admirable version of "Swan Lake," along with venturesome dramatic works by Stevenson -- "Peer Gynt" and "The Miraculous Mandarin" -- that weren't flawless but had distinctive theatrical flair. This past summer at Wolf Trap, the company staged Stevenson's production of "The Sleeping Beauty" (also known to Washingtonians in an earlier incarnation for our old National Ballet, codirected by Stevenson). Though modest in scope and means, in some ways the Houston version of this most demanding war horse seemed closer in spirit to the classical ideal than the opulent but largely wrongheaded Kenneth MacMillan production American Ballet Theatre brought to Kennedy Center shortly thereafter.

Last night's program moved decidedly into reverse gear. It opened with Stevenson's "Bartok Concerto," set to the Hungarian composer's Third Piano Concerto, and created in 1970 for the Harkness Ballet; the Houston company has performed it since 1977. It's a perfectly respectable ballet in a neoclassic vein, for a lead pair and seven other couples. It's structurally clear and fluent. It shows off the dancers' sturdy techniques without overtaxing them. The slow movement made a gently lyrical showcase for Martha Butler and Paul LeGros. In another context, the ballet might have made an entirely satisfactory curtain-raiser. On this program, though, it was called upon to serve as the most artistically substantial choreography of the evening, and it proved simply too pallid to fill the bill.

The program's concluding work -- Harald Lander's pyrotechnical Roman candle, "Etudes" -- has its potential attractions, but it's dependent upon a certain level of grandstanding virtuosity that the Houston company cannot quite muster. Li Cunxin, who was one of the three principals for last night's performance, just about qualifies, but the others -- Rachel Jonell Beard and John Grensback -- were clearly in over their heads. This isn't to say they aren't fine dancers with some laudable special qualities -- Beard, for instance, showed a lovely gentility in the adagio passages. And the company's performance in general was tasteful, refined and stylistically proper. But "Etudes" is a technical blockbuster and stands or falls on that. The Houston cast just didn't have the necessary heavy artillery.

The evening's biggest artistic disaster, despite the generous plaudits it received, was Margo Sappington's "Rodin, Mis en Vie," set to commissioned music by Michael Kamen and inspired by Rodin's celebrated sculptures (the title might be rendered "Rodin Come to Life"). This work, created in 1974, was also made for the Harkness Ballet -- what is this penchant Stevenson has for the passe' repertory of this troupe? "Rodin," danced barefoot in streaked unitards, is a ballet in name only, using a promiscuously eclectic movement vocabulary to achieve its pretentiously carnal, melodramatic effects. This is an exploitation ballet if ever there was one, achieving a nadir in the final "Gates of Hell" sequence, with dancers slithering, dangling, coiling and pretend-copulating over a five-level scaffolding aswirl with stage smoke. Kamen's equally meretricious score plunders the cliche's of Shostakovich, Sibelius, Holst, Ravel, Stravinsky and sundry pop sources.

The Houston Ballet has achieved much. The challenge it now faces -- along with many another ballet troupe across the land -- is how and where to find contemporary repertory befitting its versatile dancers and today's sophisticated audiences.