We can never really know why Schubert left his Eighth Symphony unfinished, but that shouldn't stop us from playing such a wonderful piece of music. With its deathly still opening, turbulent central section and gentle slow movement, this symphony is one of Schubert's finest and most frequently performed works.

This was Seymon Bychkov's first performance with the BBC Symphony Orchestra since they announced his appointment to their newly-created Günter Wand Conducting Chair this week, and the audience were eager to hear the fruits of this new relationship. The opening of the symphony was beautifully hushed and distant, like a cold wind, and the violins came in with an almost impossibly quiet piano which set the mood for the desolate wind tune. The music surged forwards, as it does throughout the piece, but each time I felt like the forte was shied away from. The pianos were so magical, but what of the fortes? Where was the power?

In the second movement there was a real attention to colour and phrasing with shimmering strings and a seemingly endless clarinet solo from the principal clarinet Richard Hosford. But the forte passages here were still very restrained. Perhaps most significant in this movement were some noticeable problems with intonation, which persisted right through into the last chord: not the standard I've come to expect from this orchestra.

Richard Dubugnon's Battlefield Concerto, for two pianos and two orchestras, offered a total contrast. Despite the programme note saying that the orchestras should have a visible gap in the middle, the two were placed so close together they overlapped and you couldn't see where one stopped and the other began. The result was that the "battle" of sound was not always as distinct as it could have been, though we did finally here that true forte which had been so sorely missing in the Schubert. The Labèque sisters took the title to heart: their playing was powerful and they really bounced of each other with punchy chords and rapidly explosive scales. The work as a whole seems somewhat generic and impersonal, without any of Dubugnon's usually strong musical fingerprint. The nine sections are only loosely strung together and the link to 15th-century battle paintings is unclear, and further obscured by the often jazzy nature of the material.

The final item on the programme was Richard Strauss' 1898 tone poem Ein Heldenleben ("A Hero's Life"). This musical depiction of a hero encountering his enemies, fighting them in battle, and eventually retiring is a musical rollercoaster ride, and manages to remain a musically united whole across is full 50-minute length in spite of its eschewing of standard musical forms.

The BBC SO were finally at full force and under Bychkov gave a very committed performance. The fortes were loud and soaring while the pianos were delicate and pulled on your ears, begging them to listen. The Hero's companion, in the form of a violin solo, was sensuously performed by guest leader Sergey Levitin, by turns intense and playfully virtuosic always perfectly balanced with the full orchestra. Bychkov really paced the performance well with a rapid opening section and a beautiful adagio towards the end, which never seemed to drag at all. The balance was also perfectly controlled, not only in solo moments, but in orchestral fortes, with every detail in the score coming through the texture. But in spite of all these things, this was a very scruffy performance. Some of the wind solos, most notably the cor anglais, left much to be desired, there were some issues of ensemble in the strings throughout the night, and, as in the Schubert, the intonation was poor, with the final chord again failing to ring true.

Bychkov's appointment to his new role with this orchestra will hopefully bring this incredible conductor, one of the best in the world, to London's concert halls more often, but at the moment his partnership with the BBC Symphony Orchestra is an unequal one. All the beautifully crafted phrasing, pacing and balance in the world can't make up for scruffy orchestral playing poor intonation. This new post should be a world-class orchestra working with a world-class conductor, but the orchestra I heard on Wednesday was second-rate at best.