The problem with standardized tests is it requires standardized students to be truly useful. The fact is, there are 3 broad categories of students - (A) Average students, (BA) Below Average students, and (AA) Above Average students.
A teacher who is proficient with BA students is most likely going to do poorly with AA students. Many teachers proficient with A students will have difficulty with AA students and may also have difficulty with some BA students. Any teacher who can relate to AA students is most likely going to do miserably with BA students.
Children are NOT widgets, this business-oriented approach that treats them as such is doing far more harm than good. There has to be a better way to both educate students and evaluate teachers. The Tenure system is broken because it keeps burnt out teachers in place far too long. The current push for standardized tests/evaluations fails since each student is unique. Unfortunately, since students don't appear to be taught to think creatively (since the focus is on passing tests), I doubt a practical/effective solution will be found any time soon.