Some musicians are really good, some are OK, and some are...well, they just are. Part of what differentiates is technical ability, part of it is making choices, and some of it is talent.

I used to play in the stage band for an ethnic dance company, and when I signed on, the director told me,"We have some pieces for the "A" dancers and some pieces for the "B" dancers. Everyone knows which is which but the "B" dancers." Don't know why that occurs to me just now, but it does...