Musical Knowledge vs Performances

I have rank F musical knowledge on my elf and ever since i started ranking playing, I have been able to achieve better performances. Currently rank 9 Playing. Before I ranked Playing, I could never achieve better performances.

On my human, it has rank 6 Knowledge and Rank 5 Playing. Plays better performances.

My brother, rank C playing and rank 4 Musical Knowledge, but rarely achieves better performances.

Plus, the values I added to playing instrments were from playing instrument skill, not knowledge.

I have Rank 6 MK and Rank F PI. Resulted so many terribles.

Glitched perhaps?

^For playing instrument, that's another thing.

Oh. Well, a lot of normals and a bit of excellents, but hardly inspirings.