Actually, the definition is very localized (you could be mediocre at a big co or a rockstar at a tiny backwater company) and relative. I don't think it's a stretch to assume that the majority of programmers are mediocre, the distribution curve of talent/ability not withstanding.

Yes. He was asking how to be unbiased about self evaluation. You have to paint really broad strokes to do that.

Is it perfect? No.

Do I think the 70% of programmers that probably fit this definition are mediocre? Yeah.

Keep in mind I am calling myself a mediocre programmer.