LAS VEGAS — Ten times a week, 48 weeks a year, the Cirque du Soleil spectacle “Ka” plays inside the MGM Grand Hotel and Casino here. The show, created and directed by Robert Lepage, occupies the custom-built Ka Theater, which has a capacity just under 2,000. Since “Ka” opened, on Feb. 3, 2005, more than 5.5 million people have arrived amid hissing flames and tribal drums to watch it.


It would take 1,375 sold-out performances to draw that many people to the Metropolitan Opera House. So it is unlikely that Mr. Lepage’s Met production of Wagner’s “Ring” cycle, now running in its first complete iteration, will ever beat “Ka” in spectator numbers, even if it survives temperamental machinery and temperamental critics. But it was clear after I saw the 90-minute “Ka” on Friday evening that Mr. Lepage’s “Ring” matches his Cirque du Soleil extravaganza in other, more telling and more depressing ways.


There are, on the surface, few similarities between “Ka” and Wagner’s “Ring,” besides the brandishing of a large nugget of what appeared to be gold at the start of the Cirque show and a shared fixation on twins. (Though “Ka” seems to revolve around an effort to reunite two royal siblings from the Far East after they have been separated in a shipwreck, it is notably lighter on incest than the “Ring” is.)


But despite their differences — in “Ka,” for one thing, the only sounds that come from the performers are grunts, screams and pseudo-Asiatic babble — it is nevertheless possible to see how Peter Gelb and others at the Met could have watched “Ka” and wanted Mr. Lepage to direct the “Ring.” The resources of Cirque du Soleil allowed him to create something here of genuinely Wagnerian scale and scope: an adventure tale that sweeps and swoops through the natural world with both poetry and precision, allowing viewers evocatively cinematic perspectives above and around characters as they move. (The production reportedly cost more than $200 million.) Subtle, striking interactive video projections prefigure the use of similar technology in Mr. Lepage’s “Ring.”


With a set dominated by the Sand Cliff Deck — a huge platform whose quick, smooth, magic-carpet-like pivoting is to the Met’s “Ring” planks something like what the MGM Grand is to your weekly poker game — “Ka” is particularly effective when it comes to transitions. The loud, scary shipwreck transforms seamlessly into the quiet, eerily gorgeous underwater spectacle of bodies plunging to the sea floor.


Later Mr. Lepage sets a farce scene on a sand-covered beach and then slowly, astonishingly, raises the platform so that the sand slides off, faster and faster, into the dark abyss below. Projections turn the deck, now vertical, into a forbidding cave wall.


The Met rightly saw that this gift for scene changes would suit important moments in the “Ring.” In Mr. Lepage’s production of “Die Walküre,” for example, he brings the opening storm to vivid life. We are in a sky full of dark, rushing clouds; then in the middle of a forest during a snowstorm; and then inside a hut glowing with firelight. At the end of that opera, the raked stage slowly rises and, with the help of projections, becomes a looming, snow-covered mountain.


If you think that elegant transitions like these are the crucial elements in the “Ring” — if you view Wagner’s cycle primarily as a series of logistical puzzles waiting to be solved with advanced technology — “Ka” might convince you, as it apparently did Mr. Gelb, that Mr. Lepage is the man for the job.


But if you care more about the cycle’s nuances — its characters and their relationships, its emotions, its philosophical complexities — then the idea of giving the reins to the creator of “Ka,” which is wholly devoid of all those complexities, is preposterous.


There was considerable surprise in New York at the failings of Mr. Lepage’s “Ring,” as the individual installments were rolled out over the last year and a half, but anyone who saw “Ka” should have known exactly what was, and wasn’t, coming. It is no surprise that Mr. Lepage’s dazzling, ultimately dull “Ring” looks and feels so similar to the dazzling, ultimately dull production it followed and consciously echoed. But it remains a grave disappointment — even, given the official $16 million price tag of the Met’s “Ring,” a disgrace — that with Wagner’s incalculably greater dramatic and musical material, Mr. Lepage just provided more of the same.


In both productions he often seems at a loss when the short periods of activity and transition are over, and there is occasion for reflection and feeling. His characters tend to grow aimless and bored when the set comes to a halt. Had I seen only “Ka,” I might have thought that this was the fault of the company that hired him; after all, “reflection” in a Cirque du Soleil show tends to mean a glitter-covered man in a jockstrap twirling in midair.


But in the “Ring,” too, Mr. Lepage is suspicious of the quieter parts, adding explanatory, unnecessary CliffsNotes-style illustrations to both Siegmund’s and Wotan’s long, engrossing narratives in “Die Walküre.” He is confident in the ability of his sets to hold our attention but less so in Wagner’s ability to do the same.


Of the two productions it is “Ka,” unexpectedly, that has a hint of an ideological charge. The good guys in the story inhabit an untouched nature, while the villains are depicted as industrialists: the creators of huge, efficient killing machines. This would undoubtedly have pleased Wagner, but it is a critique missing from Mr. Lepage’s resolutely shallow “Ring.”


The director has not always been so brainless: his experimental theater works in the 1980s and ’90s were widely revered. But he seems to have been caught between the poles of American culture — Las Vegas and Lincoln Center, you might call them — which eye each other with a kind of wary hunger. Each wants what the other has: immense popularity in one case, high-art respectability in the other.


Mr. Lepage has been in the unusual position of providing both. Cirque du Soleil chose him for his avant-garde cachet; then the Met wanted his crowd-pleasing panache. In both cases the results have lacked what great theater demands: something to say.