>For one, the candidate pool is artificially limited.
The candidate pool has an artificially inflated number of women due to the success of nearly universal outreach among STEM programs towards women. I'm not suggesting that's a bad thing, but let's not throw shade at universities where it's undeserved.
>And, like I said, 3 schools does not the market make.
If the 3 schools OP was recruiting from have gender bias against women then let's call them out.
Lack of diversity in STEM is a large problem, but your payroll matching the market doesn't seem like a large problem.