"With perfect equal opportunities, the mix would be the same as the mix of eligible applicants."
This is IT. The % mix of elligable applicants is heavily skewed towards white and asian males. Do you honestly think that there are 50% women applying? Or 50% black people? Or whatever ethnicity it is that is supposed to "win" today?
All we have is the current mix. Nobody has posted the % mix of elligable applicants for the entire history of the company, thus allowing us to make rational judgements about not only the current mix of applicants, but the current mix at the time individuals were hired. Senior positions, for example, require senior people.
That your current applicant mix to the company's lowest ranks might have a given diversity formula has no bearing on how the senior leadership should look. By and large senior leadership in IT is white and male (or asian and male) because those are the guys that started the industry, and they're still around. So your most senior people are still going to reflect the imbalance of their times.
If your goal is a "proper" racial/ethnic/gender/lifestyle/whatever mix then you're just going to hamstring your company. The goal should be hiring the best qualified for the job, regardless of any other considerations. And anyone taking anything else into consideration (such as race/gender/etc) should be prosecuted to the fullest extent of the law.
Checks and balances should exist to ensure they can't take such things into account. That way no biases (either "positive" or "negative", depending on your point of view) can come into play. (In theory. There's always something.)
Of course, if equality isn't your goal, then by all means, string up white males.