College professors tend to be recruited based on their ability to do research and get grants, so measuring them on teaching performance is non-threatening. However, the situation is different in K12.

Bill Gates has been able to apply his measurement philosophy at Microsoft, and the results have been disastrous by most accounts.

Here's a paper by an HR grad student slamming the practice: http://stevegall.wetpaint.com/page/Human+Resource+Management

Money quote: "Stack ranking provides questionable value as to insight into an individual’s actual job performance. Its use highly politicizes an organization. The rank number is most often based on unsubstantiated subjective judgment by an evaluator who may feel pressured to respond according to a narrow set of guidelines."

I love science. But measuring employee or teacher performance is not science. Managing an organization by pseudo-science should be called out for what it is: B.S.!