"And Treu's assertion that the tenure system discriminates against poor districts fails to address crucial 'compared to what' questions. Treu considers the downside of tenure: making it more difficult to fire incompetent teachers. But there are also upsides: most importantly, job security makes teaching a more *attractive profession to talented potential teachers*."
Well, there's the rub!
AND it's a LIE.
The tenure system specifically in California attracted AND KEPT the dredges of the intelligentsia. Every California teacher I ever met would be lucky to get a job as dog catcher, and that's before looking at their dismal academic performance, and the fact that most of their students understand math better than THEY do.
The fact is that the tenure system REPELS the best, so getting rid of it is the first step toward ACTUALLY hiring competent teachers, and FIRING them when they fail (kinda reminiscent of what used to be called free enterprise).