It's a math "problem." The overwhelming majority of people in these MOSs/designators/whatever-the-air-force-calls-them are white men; by extension, the majority of people promoted will also be white men. The appropriate, and IMO only meaningful and enduring, way to address the issue is to improve community outreach programs starting in middle school and reaching through high school. If this initiative is as important to the AF (and other services) as the most senior leaders say it is, then these measures shouldn't be difficult.