From left, Ronald Copes, Joel Krosnick, Roger Tapping and Joseph Lin of the Juilliard String Quartet (Simon Powis/Simon Powis)

Saturday’s performance by the Juilliard String Quartet at the Library of Congress could have been subtitled “Transitions.” It was the quartet’s final performance there with its longtime cellist Joel Krosnick, who will retire this summer and who represents the group’s last link with its founder and spiritual father, Robert Mann.

The program consisted of Schubert’s “Quartettsatz” in C Minor, D. 703, which pointed the way from his tuneful but formulaic early works to the shattering late masterpieces of four years later; the Elliott Carter Quartet No. 1, in which the composer inexorably turned away from music written by ear to that produced by algorithms and spreadsheets; and the concluding Beethoven Quartet in F, Op. 135, completed a few months before the composer’s death, a piece in which he smiles indulgently (even snickering at times) at earthly concerns and looks expectantly heavenward.

I’m old enough to have heard Krosnick in his first season with the Juilliard, in 1974. He was the perfect fit for the group at that time: passionately committed to new music but expressive and imaginative in standard repertoire as well. It is a different and less-focused quartet now, one that, sadly, tries to cover for the unsteady contributions of its venerable cellist. But there is really no place to hide in such an ensemble, and the indulgences harmed the music in blend, intonation and steadiness of tempo.

Leader Joseph Lin, the youngest member and in his fifth season, has grown into his role nicely. His playing initially struck me as clean but faceless, but at this concert, he impressed in every work, including in the whirling scales of the Schubert, a vivid, imaginative cadenza that ended the Carter and a deeply felt orison in the Beethoven Largo Assai. The other two members (Ronald Copes on violin and Roger Tapping on viola) are superb, veteran artists.

Carter’s principal works from the late 1940s used then-prevalent compositional techniques but were still based on melody and rhythms, including jazz. With his excessively long Quartet No. 1 from 1951, Carter drifts into glossolalia. Top musicians tackle this music because of its dense technical and intellectual challenges, but there is little for the listener to enjoy in the arid harmonies and apparently random figurations. Of this performance, all one could say was that it was “committed.”

The Beethoven had the artists back on solid ground, and it was interesting to hear some revised rhythms in the first movement based on new research. The bumptious Scherzo was outstanding, Lin again taking flight in the crazy trio section.