Well, why would those capable mid-level engineers, who probably already have decent jobs, want to interview at your company? I'm not saying this to be snarky.

Well, why would those capable mid-level engineers, who probably already have decent jobs, want to interview at your company? I'm not saying this to be snarky. If you don't have a good answer to this, that probably points to your issue. If you have to think a bit to answer that, it's probably also an issue.