Christoph Eschenbach has always paid grateful tribute to those who mentored him early in his career, and it is a credit to him that he has, in turn, often given major career boosts and long-term professional relationships to young artists in whom he sees something special. So it is that in the midst of perhaps his busiest month yet in Washington since becoming music director of the National Symphony, Eschenbach took time Monday evening to present five Mozart sonatas at the Kennedy Center’s Terrace Theater with Dan Zhu, a young Chinese violinist.

Let me get straight to the point: What was Eschenbach thinking? As someone who has regular congress with the greatest musicians in the world, he certainly knows artistry when he hears it. But after listening to Zhu all evening, in the most transparent, demanding music ever written, I am flummoxed that he would get such a high- profile endorsement and exposure. Zhu can play fast passages cleanly, but his sound is astringent and pinched. His intonation was occasionally suspect in the first half, but when he tuned sharp to the piano for the second half of the concert, as much as 40 percent of the notes he played were out of tune. He couldn’t be bothered to vibrate during the pizzicato variation in the K. 379 sonata.

Worse than all of that (other than the tuning) is that Zhu has no particular sense of singing on the instrument. He dutifully followed various unwritten dynamics and tempo adjustments of his august pianist, but never once did he produce a phrase of logic and beauty, each note growing organically out of the previous. This is a shortcoming I hear from many young string players today, but that is precisely the point: Eschenbach has inexplicably allowed a middling violinist to hitch his wagon to Eschenbach’s considerable star.

For his own part, Eschenbach showed some of the strains of his busy month, playing, conducting, and curating the “Music of Budapest, Prague and Vienna” festival. He knows Mozart, and his sincerity and well-seasoned musicianship carried the concert. But Mozart is the worst possible composer on whom to try to wing it; every tiny flaw is magnified, and while all of Eschenbach’s keyboard flaws were tiny, they were many.

From the opening phrase of the first sonata (K. 304), it was impossible to banish the thought: Why couldn’t Eschenbach make music with a real artist, namely the one who sits immediately to his left three nights a week? He and NSO concertmaster Nurit Bar-Josef could have polished these works at leisure together over an extended period and presented them as the sparkling diamonds they are, rather than this slapdash affair with an underqualified guest.

Violinist Dan Zhu. (KK Fong)

Battey is a freelance writer.