Positive impact is hard, but there are certainly terrible teachers who have a strong negative impact but are sheltered by teachers' unions. The best case is places like New York that have the notorious "rubber rooms" where they are exiled so at least they can do no further harm to students, while remaining a drain on public finances.

The problem is you can't use data science to find them. Any metric can and will be gamed. It requires a qualitative assessment, and also giving parents more power in the system, since they are the ones most aligned with the interests of students.