But he remains a curiously modest interpreter. He doesn’t achieve the architectural discipline that colleagues who similarly try to get out of the way of the music can impose, nor does he draw out sufficient clarity or detailing of consequence along the way.

Friday’s “Eroica” Symphony was typical: solid but unremarkable. Sunday’s Strauss, the 78th Boston Symphony concert for which Nelsons has programmed works by this composer, sorely lacked character, above all in the suite from “Der Rosenkavalier.” Rarely can Octavian and the Marschallin have romped so cautiously, or Baron Ochs appeared so even keeled.

Nelsons really does thrive when he has a soloist beside him, though, and that is to his great credit: Few major conductors support the artists with whom they share a stage so graciously. Gil Shaham stepped in for an injured Hilary Hahn to play Beethoven’s Violin Concerto on Friday, and gave a thoughtful reading, often seeming to perform as much for his colleagues in the orchestra as for the audience in the Shed.

Fleming returned to the stage a year after her turn substituting for the cellist Yo-Yo Ma. She again sang Strauss touchingly, offering three songs that included a magical “Befreit,” in which Nelsons hushed the orchestra to a spellbinding, steady calm. She also sang a pair of the Marschallin’s Act I monologues from “Rosenkavalier,” reflecting on the passage of time. Even for listeners seated near the front of the Shed, she was gently amplified.

One more transition demands note. The weather in the Berkshires has always been impetuous, but this past weekend was a particularly brutal one: baking heat, soaking rains, swampy humidity. Climate change affects every American orchestra, yet it must certainly affect the Boston Symphony, which depends on Tanglewood for its artistic stature and its financial stability, more than most.

Invasive beetles already threaten the trees of Western Massachusetts, including those that give the Symphony’s lands their personality and shade; a wetter, warmer summer has an impact on playing conditions, as well as on attendance and infrastructure. American orchestras generally are not doing enough when it comes to climate change. Here, as elsewhere, the Boston Symphony can lead.