In discussions regarding workplace equality, there is often the request that one should ignore skin color, gender, age etc. and just select people based on competence. This is not possible, since we have no measure of competence that is independent of an individual's observed performance, which, in turn, is dependent on the environment they operate in. Merely focusing on competence thus makes the assumption that all individuals are treated equally: that they don't face specific hurdles due to their gender, skin or age, and that they have equal access to the informal networks at the workplace - the latter being a pet subject of mine.
Take for example the Ellen Pao trial[a]: Any analysis of the events must include not only Pao's performance, but also whether she was given access to the informal networks, so vital in the business world. If she were excluded from the networks due to her being a woman - what could we expect except sub-par performance? Bringing up her performance without any reasoning as to the circumstances that performance was measured in is of little use.