NEW YORK - It's easy to forget how extraordinarily daring the Philadelphia Orchestra once was in entrusting its future to youth. Riccardo Muti and Eugene Ormandy were both under 40 when they were named music director. Stokowski was 30 (depending on when you believe he was born).

Age is immaterial to musical worthiness - or at least it should be - as two concerts at Lincoln Center's Mostly Mozart festival argued conclusively this weekend. This is an important issue to sort out as the orchestra ponders whether to go young, or makes the seemingly more practical choice of a musical grandfather with venerable name.

The question of which option is actually the safe one is rife with paradox, not to mention peril.

In Avery Fisher Hall Saturday night, Osmo Vänskä, the 56-year-old music director of the Minnesota Orchestra, led the Mostly Mozart Festival Orchestra in an all-Beethoven program exhibiting all forms of excellent choreography, but little real fire, much less penetrating insight.

Sunday afternoon came the festival's most significant debut of the summer. In his first appearance in the United States, London conductor Robin Ticciati, at 26, drew the kind of deep interpretive ideas from Mozart that few know how to mine. That he did it with an established orchestra with a strong personality, the Orchestra of the Age of Enlightenment, is all the more significant an indication that orchestra whisperers who have been touting Ticciati as one of the three or four major young podium talents are indeed right.

Physically, he's not a total natural, the way Yannick Nézet-Séguin is. That leading Philadelphia Orchestra music-director possibility, who made his New York debut earlier this month at Mostly Mozart, is unrelenting visual entertainment.

And to wade just for a moment into the superficial criteria that have attended the Philadelphia Orchestra's search, let me just say that it can only be good for Ticciati's future - he is currently music director of Glyndebourne on Tour and, starting this fall, principal conductor of the Scottish Chamber Orchestra - that he smiles a lot and is easy on the eyes. He has loose light-brown locks echoing those of his mentor, Simon Rattle, but he doesn't abuse them. These are fortunate qualities because, as we are constantly reminded, we live in a visual age, and as a podium presence, Ticciati is supremely understated. I couldn't see what he was communicating facially to his partners on stage in Alice Tully Hall in Mozart's Symphony No. 40 in G minor. But it was clear that what was heard was largely a result of what had been worked out in rehearsal rather than relying on chance, on-the-spot chemistry.

A tremendous amount was going on interpretively. All through the piece carefully scaled dynamics were deployed. Tiny pauses between sections clearly indicated the end of musical paragraphs. Slight emphasis was given to certain notes to make connections between ideas. And then, when repeats were taken, phrases given one kind of meaning were layered with additional depth the second time around.

Only rarely do you encounter performances this finely detailed with strong ideas while retaining both a fidelity to the score and a generous sense of sweep. That this orchestra is as technically assured as it is in the treacherous realm of period instruments helped enormously. No idea was technically beyond the reach of horns with crooks instead of modern valves or a brittle and primitive oboe whose sound was, against all odds, impressively controlled. Principal bassoonist Peter Whelan was an absolute master of fleet facility and a solidly plush tone of wondrous immediacy.

All of this was salient in the Mozart Piano Concerto No. 22 in E flat major (K. 482) where it morphs into a wind serenade. Robert Levin was the soloist on a fortepiano recently re-created after a model from about 1795. Levin had his challenges. The instrument went out of tune more than once, and occasionally his runs came across as muddied or partially obscured. Levin was most compelling in solo moments that granted him the space to grow quiet and introspective. In contrast, the orchestra glowed all over the place. The closing moments to the second movement were pained, hushed, and profoundly gorgeous.

Ticciati showed wisdom in Les petits riens (K. a10, attributed, if not confidently, to Mozart) that some conductors never acquire. He practically disappeared as a presence in spots, letting the musicians play stretches of chamber music in the 10 ballet movements of raucous country fun.

If you could trust your eyes, Vänskä probably would have gotten more votes as an activist conductor. Gymnastic and experienced, he is exactly the sort of conductor of a second-tier orchestra the Philadelphia Orchestra may find itself turning to in this search.

It would be nice if some representative of the orchestra would say that music is the sole, or even most important, criterion; rather, some influential members of the search team are advocating for someone willing to become a visible presence in the community, the way Vänskä has in Minneapolis or Michael Tilson Thomas has in San Francisco. What this means in practical terms always seems conveniently vague to me. It's the board's and administration's job to raise money and engage the community, and it's the music director's job to make great music.

Vänskä is, admittedly, a sight. He crouches during quiet passes, he leans nearly horizontally toward the orchestra to elicit . . . well, I'm not sure what. He knows how to get attention, as he did in the big-bang openings to the Beethoven Symphony No. 8 and the Overture to "Coriolan." After that there weren't a lot of ideas. The most developed ones came in the symphony's second movement - which brimmed with energy - while parts of the last movement were tentative and even a little slap-dash. It didn't help that pianist Yevgeny Sudbin was a force for moderation in Beethoven's Piano Concerto No. 4.

Of course, what any conductor is able to do with one orchestra is not a dependable indicator of what he can do with another. When Vänskä led the Philadelphians as guest in 2007, his personality was perhaps too strongly felt.

What could Ticciati achieve? Sadly, he's not on the roster for next season. And as far as I can tell, the only Philadelphia Orchestra representative who heard his U.S. debut Sunday was a member of the staff who got caught in the winter round of layoffs.

Sure, the orchestra is in Saratoga Springs, N.Y., three hours from Lincoln Center. But Sunday they had no concert on the schedule, and a day off, apparently, means a day off.