LENOX, MASS. — In the long-range scheme of things, the most momentous event of the Tanglewood season took place in Germany.

It happened in late June, before the Boston Symphony Orchestra had played a note. In a dispute with music director Christian Thielemann, Andris Nelsons walked out of rehearsals for a new production of "Parsifal" at the Bayreuth Festival. The rupture left him free to announce last Sunday that he will spend four weeks next summer at Tanglewood, working with both the BSO and the student orchestra.

The commitment represents only one week more than the well-liked music director spent here this summer — two weeks more than he was down for before the Bayreuth split — but it is significant artistically. The difference Nelsons makes was marked when he arrived in the fourth week this summer to conduct three concerts on consecutive days.

The BSO season up till then had been an up-and-down affair, some concerts good, some less good. With a powerful Mahler Ninth Symphony, Nelsons infused new energy into the playing. The weekend culminated in an impressive Brahms program with the Tanglewood Music Center Orchestra and Paul Lewis as piano soloist.

From that point on, though Nelsons went home for the next three weeks, BSO programs generally surged ahead in interest and quality. The absence from Bayreuth yielded its first reward when Nelsons was able to stay on for a third week to conduct the closing day's Beethoven Ninth. It was a peculiar performance, ponderous and chorus-heavy, but it showed Nelsons trying things out, a necessity for growth.


Lots of good things happened in the Shed, but for this listener, the most extraordinary sequence of events was three programs in Ozawa Hall in the four days Aug. 15 through 18.

First, Charles Dutoit, the summer's Koussevitzky Artist, conducted the Music Center Orchestra in a brilliant program culminating in Stravinsky's "Rite of Spring," but also including a dazzling solo performance of the Tchaikovsky Violin Concerto by Gil Shaham. Shaham returned two nights later with a deeply immersive performance of Bach's complete violin sonatas and partitas. The next night, Dutoit led a staged performance of Stravinsky's "Soldier's Tale" that was magical in both senses of the word.

Against this, the season's lows were two programs designed to show off personalities. One was oboist Francois Leleux's chamber music program spotlighting Francois Leleux. Similarly disappointing was "Barry Humphries' Weimar Cabaret," which was as much about Barry Humphries as Weimar-era cabaret.

Tanglewood continues to expand its popular attractions — both Popular Artists and Pops — but also continues to schedule them outside the eight-week BSO season. It's questionable how many pop fans cross over to classical.

But in response to audience pressures, BSO programming also seems to be trending more toward popular, with celebrity artists — Yo-Yo Ma is a perennial favorite — and old warhorses. The Tchaikovsky Piano Concerto, for example, was back this year (in a sizzling performance by Garrick Ohlsson).

Still, the BSO was able to work in several impressive debuts, of both conductors and soloists. And new music provided variety and adventure. There was, for example, the American premiere of George Benjamin's "Dream of the Song," performed by TMC musicians.

Though not a sock in the gut like Benjamin's opera "Written on Skin," an American premiere by the TMC in 2013, "Dream of the Song" also cast a spell blurring the lines between past and present, real and unreal. On the same Festival of Contemporary Music program, the TMC Orchestra went on to Messiaen's ecstatic "Turangalila" Symphony, an 80-minute rarity.

For its part, the BSO took on John Adams' "Harmonielehre, a riot of ecstasy and color. At an opposite end of the spectrum, the justly durable Emerson String Quartet began its 40th-anniversary season with back-to-back programs of Haydn and Viennese composers.

Without giving specifics, Nelsons announced plans for two opera projects next year. A BSO concert version of the first two acts of Verdi's "Aida" this year suggested the challenges ahead.

With Nelsons conducting and his wife, Kristine Opolais, singing the title role, "Aida" was his first extended go at opera here, though he has done much with it in opera houses and Symphony Hall. Opolais sang nobly, and the rest of the cast measured up as adequate or better. But, perhaps because of limited rehearsal, the whole thing seemed put together on the fly. The effect was static.

We'll know more about where Nelsons is taking the festival and orchestra when the 2017 season is announced in November. Meanwhile, the good news for music lovers is that we'll see more of him next year. How does the BSO feel? You can hear it in the playing.