for me, the rejuvenation of Boston SO has been most welcome - talk about a downward slide!! The BSO really declined under Munch [he hated to rehearse], discipline got really sloppy, poor ensemble...The Management in its attempts to get things back on track hired Leinsdorf, who simply wasn't up to the job....They needed a Reiner, Monteux or Steinberg, but those Maestros were already committed elsewhere. the decade or so of Leinsdork was a real plunge downward....poor playing, morale plummeted, the standard sunk probably to its lowest.
Steinberg finally came in, but he was past his prime, and soon retired...The orchestra did improve somewhat under Ozawa - good and bad, but it never really got to the top levels - perhaps he just stayed too long...Ozawa had a major problem making up his mind re filling vacancies....this constant vacillation, refusal to commit, was detrimental to the ensemble. Same problem plagued him in San Francisco..
Levine really kicked life into the orchestra - there was an immediate upturn in energy, alertness, ensemble....I know that audience didn't care for his programming - lots of modern works, but the orchestra responded favorably. Nelsons has continued this, and the orchestra is sounding very good at present. It is fun to hear them, I've heard lots of fine performances - still room for improvement, of course [woodwinds]....but the trajectory is "upward" for sure.