I would like to describe a research study in which I participated because the results speak to this issue. A portion of our very large school district conducted an experiment with an innovative writing test of its own design at grades 4, 8, and 10, and our team analyzed the results. We could not publish the results outside the school district because the size of the study meant it would be too easy to identify individual participants and their individual results, so I cannot link to it.
The basic results were publicized, and they showed that 57% of the students scored at a level of 3 or 4 on a 4-point scale, meaning 43% either did very poorly or showed a need for improvement. The individual teachers involved got a report telling them how their students did, but they were not given a report on how any other teachers' students did. What they did not know (but we did), was that not a single teacher in any of the grades had students score anywhere close to 57% proficient or better. Every teacher scored either in the 90% range (or above) or the 20% range (or below). All teachers were teaching mixed ability classes.
We did an anonymous survey to get the teachers' responses to the test. Because we knew of the tremendous disparity in results, we were able to know with good precision how the anonymous teachers taking the survey had done because the first question we asked was how they felt their students had done. On a 5-point Likert scale, every response was either a 1 or a 5. That meant we could then sort all their other responses by the quality of their students' performances.
For one question, we created 5 different philosophies of education, worded as objectively as we could, and asked them to choose which matched their beliefs most closely. The results were unanimous. Every single one of the teachers whose students had done poorly said that the primary factor in student performance was student ability, and there was little to nothing the teacher could do to make a difference. Every single one of the the teachers whose students had done well said that all students had the ability to succeed at a high level, and it was the job of the teacher to find and apply the best instructional strategies to make that happen.
So, if you were a school district administrator of a school district receiving that report, would you look at changes in your system to improve results, or would you hope you got better students to improve results?