Christoph Eschenbach and the National Symphony Orchestra, with Morgan Freeman, center, perform "Remembering JFK: (An American Elegy)." (Tracy A Woodward/WASHINGTON POST)

There are a lot of ways to talk about an orchestra’s sound. You can analyze the quality of the various sections; talk about the way those sections play together; point out strengths and weaknesses among the principal players. But there are intangibles, as well.

Five years ago, the National Symphony Orchestra didn’t sound like an orchestra that was having fun. Now, under Christoph Eschenbach, it does.

That’s not to say there aren’t some technical issues — with the orchestra or Eschenbach. On Thursday night’s program at the Kennedy Center, balance between sections was a problem: The brass overwhelmed the strings in sections of the suite in Richard Strauss’s “Rosenkavalier” and in the final movement of the Beethoven Seventh. At times, Eschenbach slowed everything so much that the music seemed to crawl.

But at least something was happening, almost all the time, and quite a lot of it was good. Offsetting the balance issues in “Rosenkavalier” and the smearing of sound in big sections — as if someone had wiped a big gob of Vaseline over the lines of this already wonderfully goopy score — were moments of absolute gracious lightness. The music that accompanies the presentation of the rose in the opera, the epitome of teenage romantic fantasy, was as shimmering and magical and genuine as you could wish — and Nurit Bar-Josef, the concertmaster, brought both grace and warmth to her solos. Washington heard the Vienna Philharmonic play this piece under Lorin Maazel a few months ago; in terms of emotion, this reading stood up well to the competition.

Eschenbach’s Beethoven was clearly conceived with an eye to the whole. The transitions between movements were handled so deftly that the pauses became contributions to a larger narrative rather than interruptions between four separate entities.

Germany's Christoph Eschenbach conducts the Austrian Wiener Philharhoniker during the final rehearsal, hours before the orchestra's only concert of the year in Scandinavia on October 14, 2008 at the Aalborg Congress and Cultural Center. (HENNING BAGGER/AFP/Getty Images)

The program, which is also a run-through for the orchestra’s upcoming South American tour, began with a world premiere: “Blue Blazes,” by Sean Shepherd. Shepherd, 33, is the composer-in-residence with the Cleveland Orchestra, and this piece is, notably, the second work by him that the NSO has played this season; Oliver Knussen conducted “Wanderlust” in November.

Like many new commissions (it came thanks to the NSO’s Hechinger Commissioning Fund), this piece was short. And like many short works by eager young composers, it was so overfreighted with ideas and so eager to make its point that it sometimes got a little tedious.

Stylistically, the piece follows the polymathic, exuberant, slightly slick model that’s become a kind of default for young American orchestral composers striving to show proficiency on the one hand and a wide range of influences on the other — in this case from John Adams to jazz to cartoons (my companion likened its helter-skelter progress to a Disney chase). Its strongest moment came toward the end, when the textures thinned out and a quartet of principal strings, backed up by winds, allowed some air to come in for the first time since the plucked pizzicato of the opening was answered by the humid lowering of brass. Still, it’s a good sign when a young artist’s best moment is in the slow part, which is usually harder to pull off. And there’s no question that Shepherd is a composer worth watching and hearing, even if this particular piece might not be the one that you want to hear over and over again.

The night also marked some transitions for the orchestra, honoring the impending retirement of three musicians who, together, have chalked up 119 years of service: the principal flutist, Toshiko Kohno; the cellist David Howard; and the principal percussionist, F. Anthony Ames, who joined the orchestra in 1968. With the impending departure of the principal horn player, Martin Hackleman, who is leaving to take a teaching position at the University of Missouri, this means changes of three principal positions, which will give Eschenbach a chance to put his stamp even more on this orchestra.

Eschenbach’s musical stamp is constantly shifting. In the third movement of the Beethoven, he opened with a refreshing, rousing account of the presto; switched to a second section that sounded downright lugubrious; brought back the original theme in a much lighter, more delicate vein; and then belabored the contrast between the two until one was almost sick of it.

There’s no question he has a lot to say, and no question that he’s utterly in the moment. And there’s no question that the musicians sound as though they’re going right along with him. That, at the very least, is something to work with.

The program repeats Friday and Saturday at 8 p.m.