I've been in situations like that. For me, it's like interviewing, I just keep backing off, lowering the bar, making it easier and easier until they can get it

I've been in situations like that. For me, it's like interviewing, I just keep backing off, lowering the bar, making it easier and easier until they can get it, then start going back up again. I pretty quickly get a confident read on where they are. If at that point it's clear (to me) the situation is not salvageable, it's a management issue, I've done my job.