I've proposed (and been rejected) where I work that we have both high and underperformers go through mock interviews for their roles, to see if our interview questions could distinguish who was who.

I understand that this is going to be awkward, especially for the low performers, but at the moment I don't think our interview practices are based on anything. We ask questions and then later have a conversation about how and whether or not our questions revealed the presence of the attributes we were supposed to be assessing for and it feels very made up and make believe. Plus, people could be given incentives for going through the process and bonuses for passing the mock interviews to encourage them to try

If we could get people where we already knew how good or bad they were to rerun the interview process then we could start to figure out which questions and which evaluation methods were useful in separating good candidates from poor ones.