You can't measure it before you join, just as they can't measure your effectiveness before you join. The best you can do is hit the eject button after 6 months after you've assessed what's really going on. Same goes for the employer's side.
You can generate heuristic data though. This really should be a priority for you during the interview process. They have the right to ask you very difficult questions, and you have the right to ask them very difficult questions as well.