There are only three ways to have a workforce significantly more diverse than your applicant pool:
1) Get lucky, and have the best candidates just happen to have the particular immutable characteristics of birth you think qualify them for a job. In which case, congratulations? But it's nothing to brag about. And it's only possible for low-n. The law of averages will wipe it out sooner or later.
2) Intentionally hire suboptimal candidates because they have the immutable characteristics of birth you think qualify them for a job. Congratulations, you made your company worse.
3) Spend an inordinate amount of time interviewing candidates in order to find ones who are both excellent and have the immutable characteristics of birth you think qualify them for a job. Congratulations, you made your company worse. Time and effort are finite resources and you should have been spending yours building better products and connecting with your customers.
All this, for what? Plaudits in the tech press? Maybe attracting investment from VC firms that say they want their companies to employ people with a wide range of immutable characteristics of birth? You haven't made your products better, and you haven't connected with your customers more. You've either hired a worse team or wasted your time.
If, for sufficiently large n, your workforce does not look like your applicant pool, you have broken hiring practices.