Some concerts leave you with a mental note: Catch up later with all concerned parties. Even if you weren't entirely happy with what you heard, the future looked promising.

So it was at the Philadelphia Orchestra's Friday afternoon concert at the Kimmel Center, generally for the music of composer Behzad Ranjbaran and specifically for guest conductor Robert Spano's relationship with Jean Sibelius.

Ranjbaran, 55, a seasoned composer born in Tehran and now living on Long Island, has received major concerto commissions, among them his Piano Concerto, written two years ago for Jean-Yves Thibaudet. At Friday's Philadelphia premiere, the concerto seemed too concerned with keeping up with Liszt, Tchaikovsky, and Ravel (don't we hear enough of those dead guys?), though at times, a distinctive compositional voice made itself heard.

The concerto's long, eventful first movement had the kind of darkness one might expect from a onetime political prisoner under the Shah of Iran. But with such obvious antecedents, your ear couldn't get past the music's surface. When you thought you were getting somewhere in the piece's inner world, one of the three Lisztian cadenzas stomped in. As great as it is to hear a pianist of Thibaudet's caliber storm the balcony, the music felt like conscious manipulation rather than compositional fantasy.

Ranjbaran's second movement was the work of a far more authentic composer: The music knew exactly what it was about, with melody and harmony drawn from, but not shackled to, Persian roots. Proportions felt instinctively right. Maybe your ear didn't know where the music was going, but the composer did.

Such qualities carried over into the third movement, though after a certain point, the composer was wrapping up business with a reprise of the opening motif (reminiscent of Tchaikovsky's Manfred Symphony). With Ranjbaran having embraced tradition in this piece, one hopes he will go on to transcend it.

The rest of the program was Sibelius, whose Nordic temperament suits the time of the winter solstice, though the opening piece - his late-period incidental music for The Tempest - played oddly. Though written for Shakespeare's last play, Sibelius' score occupies more of a Cymbeline-ish place in his output - reprising past musical effects with a splintered heedlessness that made you more attuned to the lack of integration in Ranjbaran's concerto.

In Sibelius' masterful Symphony No. 5, Spano downplayed the music's descriptive elements (such as the famous portrayal of huge flocks of birds arising over the bare landscape) and let the architecture carry the piece. In this symphony of ostinatos, Spano gave the repetitive qualities a hypnotic lack of exterior drama, particularly during Dan Matsukawa's excellent bassoon solo. The music felt strange, welcomingly so, for being a bit cerebral. But in closing moments, Spano resorted to an emotionalism that wasn't consistent with what came before. Was he worried that the audience might feel cheated by his intellectual chill? I think it's a chance worth taking in the future.