I spent 9 years in some of the worst public schools in America until I was able to escape to a private school.

I think you completely underrate the very real problem of bad teachers in poor cities. This is not just teachers merely being unable to teach kids with all manner of problems - there are many teachers who are actively making things worse, in many cases being both verbally and physically abusive to the students.

The very real problem of teacher evaluation does not in anyway obviate the fact that many teachers in poor communities are more horrible than most would dare imagine.