"Merit assessment" of teachers opens up whole new horizons for abuse of power.
What about the incompetent principal or dean or school VP who holds a grudge for being continually proven wrong, and now has the power to do something about it?
You've heard of the term "teacher's pet", I am sure... Well, get ready for "principal's pet", "dean's pet", and "VP's pet", etc...
You think you just got rid of incompetent teachers, but all you did was open the door for favoritism.
Say goodbye to professionalism and collegiality.