Led by its audacious music director, Joana Carneiro, the Berkeley Symphony offers the most imaginative programming of any Bay Area orchestra, hands down. Other ensembles could take a cue from Carneiro, whose forays into late 20th- century works, as well as her regular commissioning of brand-new ones, could be a template for contemporary orchestras.

In her fourth season as Berkeley's music director, the 36-year-old Portuguese conductor is charismatic, a dynamic figure on the podium. And her audience is ready to follow her.

But, you have to execute.

Thursday's program at Zellerbach Hall was a mixed bag, often sloppily played. Exciting on paper, it presented a new commissioned work, "Invisible Skyline," by 21-year-old Berkeley-bred composer Dylan Mattingly, a protégé of John Adams; the Concerto for Piano and Orchestra by György Ligeti, the Hungarian master who completed this bracing piece in the late 1980s; and Robert Schumann's heroic Symphony No. 2 in C major.

Ligeti fared best, which is saying something, as this is an outrageously complex piece. Before the performance began, pianist Shai Wosner -- the unshakable soloist -- offered some perceptive comments. He spoke of Ligeti's way of creating "an illusion of multiple speeds." Wosner compared the effect to that of a bicycle wheel, which spins so fast that, at a certain point, it begins to look as if it is spinning backward.

Carneiro drew a transparent performance from the small orchestra for which the piece is scored -- only a dozen or so players, including an array of percussion and a clarinetist doubling on ocarina, the ancient egg-shaped wind instrument. Watching the musical events onstage helped this listener keep track of Ligeti's narrative: his strange timbres, which occur in unusual combinations, his unexpected gestures and piled polyrhythms -- a carnivalesque assemblage.

I was engrossed, especially in the middle movements (there are five), when the piece became a sumptuous maelstrom. The slow second movement -- it's been compared to Bartok's "night music" -- begins with a long bowed note on double bass, almost inaudible. This is joined by murmured melody from the flute, sighs from the ocarina, the shout of a slide whistle, and finally a slow succession of notes from the piano, which gather momentum and begin to cluster and drip. It sounded like an exotic choir of birds.

In the third movement, the piano's perpetual motion combined with floating winds and xylophone to mysterious effect, like radio signals arriving from outer space. When the unexpected whack of a woodblock ended the brief finale, this listener felt as if he had been snapped out of a trance.

With its exaggerated and unusual gestures, Ligeti's piece might be compared to Kabuki theater. At least to these ears, that comparison does not fit Mattingly's new piece, though he told the audience that "Invisible Skyline" strives to be just that: an "imaginary Kabuki play," a "voyage" to a state of mind where fiction merges with reality, where there is a suspension of disbelief.

A student at the Bard College Conservatory of Music in Annandale-on-Hudson, N.Y., Mattingly has built an impressive record of commissions. I've enjoyed his jaunty and shimmering compositions on "Stream of Stars," a recent CD from the ensemble Contemporaneous. "Invisible Skyline" again explores oscillating textures and colors as it floats and evokes a mood of tenderness. But it strikes me as cautious and something of a retread -- across three movements (he titles them "acts") and nearly 30 minutes.

We've heard this before: pointillist, pulsing textures, with ostinatos a bit too reminiscent of Steve Reich; long-lined declamatory melodies that sound an awful lot like Adams. It might be time for Mattingly to push away from home port and begin his voyage toward a more personal voice. (Another of his new works will be premiered Saturday in San Francisco by the Del Sol Quartet.)

If the composition was cautious, so was the performance. I imagine the 80 or 90 players onstage were stressed out counting rhythms. There are points in the score where the string section is divided up left and right; independent time signatures abound. Still, this is a professional orchestra, and it wasn't taking care of business. Carneiro didn't draw massed power or nuanced texture from her forces. At a crucial moment in the finale, the horns were a mess.

As for Schumann's Symphony No. 2, on one level, it's always a treat to hear this work, which is so redolent with melody, yearning, drama. Carneiro clearly loves the piece, and her players seemed to put their souls into it. But the performance, again, was imprecise. In the scherzo, the flying string theme was poorly articulated, at times a smear. Perhaps aiming for extra nobility, Carneiro slowed the adagio to the point where all the rough edges were audible.

Contact Richard Scheinin at 408-920-5069, read his stories and reviews at www.mercurynews.com/richard-scheinin and follow him at Twitter.com/richardscheinin.

Del Sol String Quartet

Playing a new work by Dylan Mattingly

When: 8 p.m. Saturday
Where: Z Space, 450 Florida St., San Francisco
Tickets: $30 general, $25 seniors, $15 students; www.delsolquartet.com or at the door