Actually, based on my experience of dealing with hundreds of teachers and thousands of students, that won't work either. Test scores are a poor proxy for what students actually know or can do, especially in mathematics. The original linked article provides evidence for that. You put in the caveat "Of course ... this won't work for all districts" but then you're arguing for exceptions to be allowed. That's just a mess.
There is no simple fix. There are bad teachers (and I'm leaving the term undefined - it's a bit like porn - undefinable, but recognisable) who get good test results and glowing evaluations, and there are superb teachers who get mediocre test results and undistinguished evaluations.
It's easy from the outside or from a limited perspective to suggest "obvious" methods of assessment or "obvious" actions to improve the situation, but in the end, no one has really defined what they mean by "good teaching," so proposing assessments of something undefined will just result in more proxies to be distorted.
There is no simple fix. There are bad teachers (and I'm leaving the term undefined - it's a bit like porn - undefinable, but recognisable) who get good test results and glowing evaluations, and there are superb teachers who get mediocre test results and undistinguished evaluations.
It's easy from the outside or from a limited perspective to suggest "obvious" methods of assessment or "obvious" actions to improve the situation, but in the end, no one has really defined what they mean by "good teaching," so proposing assessments of something undefined will just result in more proxies to be distorted.