My point is don’t actively screw those people by coming up with a dumb compensation formula that punishes them for students underperforming before they ever entered their class. If you have merit based pay you need to evaluate how much a student improved under a specific teacher’s watch.

Even a blunt results based compensation would be far better than the current situation.

It wouldn’t if the obvious consequence of the bluntness was to chase good teachers out of the schools that most need them. And that’s what a blunt policy that punishes teachers for having students enter their class at a low level does.