A Disappointing Article From Brookings

Is there hope for math education in the United States?  I was all set to read some good news in this article from Brookings, and then I got to this:

To assess whether teachers’ mathematical knowledge changed over time, we compared results from surveys we fielded with middle school teachers in 2005 and in 2016. Both surveys captured teachers’ mathematical knowledge for teaching (MKT). Although these surveys used two separate samples, both were designed to be nationally representative and thus allowed comparisons in teacher MKT over time.

MKT.  Geez.  Of course, teacher knowledge is a necessary but not sufficient condition of being able to teach, but here's what I've written in the past about MKT:

What attributes make a good math teacher?  That was the title of one of my research papers for one of my master's degree classes.  It was a review of literature, and here's the conclusion:

There are no definitive skills, knowledge, or attributes that have been identified, the possession of which will, ipso facto, make a good math teacher. There is no known way to predict in pre-service who will become a good math teacher, and there is no known protocol (such as the MKT) for determining effective math teachers. Furthermore, popular pedagogical styles do not seem to improve student performance, so the teachers who employ them cannot rightly be deemed effective.

Good teachers are good because they get students to learn, not because they have certain knowledge or skills.  Student performance and gains are what is important in determining if a teacher is good or not.

The Brookings article focused only on teachers and teaching, not on student performance:

To mathematics educators who have been in this business since the 1990s, as I have, these results are cause for both hope and dismay. Hope because modest movement toward standards-aligned instruction did appear. Hope also because this movement appeared where expected: in districts that aligned professional development, curriculum materials, and messages from leadership over long periods of time to create conditions under which their teachers could learn. Dismay because these changes appeared quite modest, both against a baseline of reformers’ expectations and against classroom data collected in 1999. Evidence also suggests only small improvements in teachers’ mathematical knowledge and limited take-up of standards-aligned curriculum materials.

I guess the title of the article, which mentions math instruction, should have clued me in to their focus.  But who cares if teaching is getting any better.  Are students doing any better?  And if they're not, is it because of bad teaching, or some other reason?