It is so easy to game the process or interpret results in different ways that there is no real single standard measure for something like this. And the "standardized testing" in the US is definitely not perfect. So really all any of us should focus on is helping where we can at the local level to ensure the teachers and students have the support they need to do the best they can.

And one last note, good teaching is not always going to result in good standardized testing scores. The fact is that kids have different levels of ability in each subject. So a great result for an average kid may not be a great overall score, but for that kid it is success (and that is what should matter the most).